Thank you for your feedback. This all makes sense.

Initially, I found some on-page SEO errors and attempted to fix them. Eg. alt text was missing from many images and most of the image files were too large, affecting site loading speed.

But after fixing them and getting a 100/100 site health score from Ahrefs, I received the notice from Google. I was confused.

Yes, I was sending readers to a number of affiliate products from Clickbank. Now I'm thinking, after you mentioned, maybe that was the reason it got flagged.

I'll look into it again. Once again, thanks a lot for pointing out the possible reasons.