I can't recall seeing ads on the Android app, but there are definitely ads in the web client. The ads must do a very good job of disguising themselves if you haven't noticed them. I have moved most of my email to ProtonMail. So much nicer paying for that from a company that respects me rather than using a free product from a company who has no other purpose than to drive ad revenue.
I’ve never seen ads. I believe the difference (and potential explanation as to why GP hasn’t seen any either) is that my account is through google workspace.
The ads are in the android app if you select a "smart" tab, like the Social or Campaigns (and I pay for google one, still get those ads). Fortunately I'm never in those tabs on the mobile client.
