Having a bit of experience with various mobile games (always from f2p perspective), ads are usually not imposed to users - if you play them, you get some rewards, that's the usual scheme.
I had mobile pes installed in first 2 seasons since they released it, but never got into playing it, was just curious.
The thing is that you have limited "energy" pool and each match consumes some energy. No energy - no plays - either wait for it to recover slowly (hours and hours) or pay with $$$ - or watch an advertisment and e.g. receive small amount of energy.
There were no ads in those 2 seasons, when i had it.
One more thing about mobile PES - it is the same title (service you might say), which just gets new branding each year. I'm pretty sure that those 100+ million of downloads are CUMULATIVE downloads from the Day 1 (about 4 or 5 years now). With new "season" the tally in store never fell to 0, it simply continued to grow.
Also about seasonal resets - don't know if it got changed, but at the end of season 1 nothing terrible happened to my team. I kept everyone I had, with warnings that certain players or managers might be gone, since they are not available in Season 2 (licensing, ...). So, it could have been trainwreck had i collected Borussia Dortmund crew in 2017 and then in 2018 Dortmund is out, back to EA.
No forced team wipe, but individual mileage might vary, depending on the team. You got some random replacements, but hey ...