Hi.
Apologies if I am pointing out the obvious but your initial drop looks like it is due to the June core algo update.
So it's not natural in this case.
You could be chasing your tail a bit trying to figure out what it could be as a lot of sites who were initially dropping in June have made a bit of a recovery in the September update:
https://www.sistrix.com/blog/google-core-update-september-2019-first-results-visible/
Sorry I cannot be of more help but will update when more is known about the September update 'winners and losers'
