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RFLTyler

Thanks for the question. I think this brings up a really good point when it comes to the review platform space.

As you mentioned - it appears that Yotpo is doing this to track clicks back to you (that's why they 301 redirect).

If I were in your shoes, I would take one of 3 approaches (from least to most risk-averse):

Don't worry about the links - There are plenty of websites out there that spin up copies of your website that the engineers at Google are brilliant enough to filter those out of your Google Webmaster Tools (GWT), they'll eventually get these Yotpo ones as well.
Email the support team at Yotpo and see if they can "no-index, no-follow" the 301 redirect links that go back to your website. This is happening to you and it's happening to everyone else who is using the system. If they really want to provide a long-term review solution, this is INVALUABLE feedback that they can get.
Disavow the links. As Eric and Deacyde above mentioned - you can go through a full analysis of the links and disavow them or disavow the entire domain.

I like taking a data-driven approach, so here's how I would decide:

Look at the impression data in GWT from Before/After you started using Yotpo. Look at a few of your best performing pages, that also have reviews pointing to them (very important), and see if (seasonally-adjusted*) the impressions are down.
If you started using Yotpo>90 days ago, you cant using this technique due to the data limitations in GWT.
I would pick a handful (maybe 10) pages to review first - look at ones that are the highest traffic/impressions.
If Impressions have bottomed out (seasonally adjusted) for these pages - disavow the domain AND email the support team at Yotpo. Here are the instructions straight from Google. Use the domain:yotpo.com flag in your file.
Look at the Organic session/user data in Google Analytics (GA) from before after you started using Yotpo. Use the same criteria here as you would GWT, about 10 pages, that have a decent number of monthly visits (>300).
If your data is small - this probably won't help much as any change could cause a big swing in it.
If your Organic sessions have bottomed out (seasonally adjusted) for these pages - disavow the domain AND email the support team at Yotpo.
If you are unsure about #1 and #2 - email the support team at Yotpo and ask them to noindex/nofollow their 301 redirects. They owe it to you as a customer NOT to mess up your SEO.
If you are ok with a little risk, then don't worry about it for now and monitor continuously.

A word on seasonally adjusted data - I worked with a Ski Gear/Equipment company in the past and we saw very dramatic swings in traffic from November - February. You are probably seeing something similarly. If your work with Yotpo started during the "high season", I'd recommend seasonally adjusting it (divide the monthly session data by the % that Google Trends gives for that target keyword, in country. Yes - it's ALOT of work, but it will give you a precise idea). Since you posted this question in April, I presume that's soon after you started it and I would recommend only having your "before" traffic start sometime in Mid-March, after the high-season and into the shoulder season/summer. Weather and all other seasonality does play a factor here, but without the data telling you what's going on, you could either over/under panic and no one likes extra anxiety!

Let me know if this helps!

RFLTyler

Thanks for the question. I think this brings up a really good point when it comes to the review platform space.

As you mentioned - it appears that Yotpo is doing this to track clicks back to you (that's why they 301 redirect).

If I were in your shoes, I would take one of 3 approaches (from least to most risk-averse):

Don't worry about the links - There are plenty of websites out there that spin up copies of your website that the engineers at Google are brilliant enough to filter those out of your Google Webmaster Tools (GWT), they'll eventually get these Yotpo ones as well.
Email the support team at Yotpo and see if they can "no-index, no-follow" the 301 redirect links that go back to your website. This is happening to you and it's happening to everyone else who is using the system. If they really want to provide a long-term review solution, this is INVALUABLE feedback that they can get.
Disavow the links. As Eric and Deacyde above mentioned - you can go through a full analysis of the links and disavow them or disavow the entire domain.

I like taking a data-driven approach, so here's how I would decide:

Look at the impression data in GWT from Before/After you started using Yotpo. Look at a few of your best performing pages, that also have reviews pointing to them (very important), and see if (seasonally-adjusted*) the impressions are down.
If you started using Yotpo>90 days ago, you cant using this technique due to the data limitations in GWT.
I would pick a handful (maybe 10) pages to review first - look at ones that are the highest traffic/impressions.
If Impressions have bottomed out (seasonally adjusted) for these pages - disavow the domain AND email the support team at Yotpo. Here are the instructions straight from Google. Use the domain:yotpo.com flag in your file.
Look at the Organic session/user data in Google Analytics (GA) from before after you started using Yotpo. Use the same criteria here as you would GWT, about 10 pages, that have a decent number of monthly visits (>300).
If your data is small - this probably won't help much as any change could cause a big swing in it.
If your Organic sessions have bottomed out (seasonally adjusted) for these pages - disavow the domain AND email the support team at Yotpo.
If you are unsure about #1 and #2 - email the support team at Yotpo and ask them to noindex/nofollow their 301 redirects. They owe it to you as a customer NOT to mess up your SEO.
If you are ok with a little risk, then don't worry about it for now and monitor continuously.

A word on seasonally adjusted data - I worked with a Ski Gear/Equipment company in the past and we saw very dramatic swings in traffic from November - February. You are probably seeing something similarly. If your work with Yotpo started during the "high season", I'd recommend seasonally adjusting it (divide the monthly session data by the % that Google Trends gives for that target keyword, in country. Yes - it's ALOT of work, but it will give you a precise idea). Since you posted this question in April, I presume that's soon after you started it and I would recommend only having your "before" traffic start sometime in Mid-March, after the high-season and into the shoulder season/summer. Weather and all other seasonality does play a factor here, but without the data telling you what's going on, you could either over/under panic and no one likes extra anxiety!

Let me know if this helps!