I don’t see an option in the android app to affect rules and I don’t remember ever making a rule in the web version.
The only thing I ever changed was to flip on the “conversation view” in web version.

A setting to arrange conversations newest on top, please.

Also, maybe someone here knows what this problem is:
I recently sent a few emails to recipients and they went to the sent folder after, as expected.
But replies to those emails from the recipients do not come into the Inbox, I can only find them in the Sent folder afterward.
What gives?

Proton subscriber for, maybe 5 years(?) here. I don’t recall ever seeing an ad specifically in the app. That said, I must have seen an ad either in the app or by email, because that’s how I was introduced to proton Pass, which I now use and I’m glad I was introduced.
Were you logged in at the time?
First thing to do with any new program is go to settings and set all notifications and privacy and opt-out stuff the way you want.