It feels like AI completely ignores the player and doesn't notice him - a lot of accidents because AI doesn't use the brakes. This is very noticeable on corners, if you do not follow AI-line. In general FR90 is the best of the existing Formula classes in all games and only AI so much is upsetting.
Example, at which track? What is your AI setting? Otherwise I would say you brake to early or your cornerspeed is to low. These are formula One cars, brake as late and hard as possible and keep the cornerspeed as high as possible.
Mostly Zolder, Zandvoort and Nurburgring. AI 97. Yeah, you're right - open wheels aren't my class(but love in), I drive very mediocre in it. But even the stupid AI in the RF2 and F1 2019 tolerates it.
Try to teach the AI with your speed, do a few races (a 10 minutes) with different AI setting f.e. 95 - 97 - 99 - 101, and then set the AI to Adapted AI start every race from those "trainingsraces" from the back of the grid, do a "late start", let the AI get a few seconds, and than only try to follow the the field with clean laps.