Anyone else get this warning?

I started playing again after 1.5 years without, after 3 days I see this warning sign every time I sign in.

I have no clue how to go about hacking anything, but if they continue to think I am, then eventually I’ll be banned from the game?

Not sure how to prevent this from happening.

Did someone hack my account and is using it? Idt I see any new Pokémon;

Is my ios somehow out of date or something?

I first got the notice as I started up the game while getting out of an Uber, could the Uber app have somehow messed with the Pokémon Go app? Seems unlikely but trying to think of anything