A mix of F1 2019, 2017 and 2012.
2019 (and previous games to a point) had contract-bound qualifying & race goals where you had to finish, at a minimum, the position the team sets for you in your contract (and subsequently you agree on in future contracts, using it as a negotiation device). Gave races an extra dimension where you were under pressure to perform and you knew exactly where to aim for as a driver. That ended with 2020 and the races have felt empty and aimless since.
2019 also had the start of driver transfers, although now it's great to have the F2 drivers coming through as well.
2019 & 2017: classic cars, going back to the 1970s. Bring them back along with ability to make multi-class championships again. I have zero interest in supercars.
2017 (and previous games) had a more realistic drive-offer system where teams would come in and make an offer for you to join them. Along with race goals, it gave you a sense of achievement if a big team came in for you and that you couldn't just go anywhere no matter how bad a driver you are (unlike now).
2012, localized weather. Fond memories of wet weather hitting sector 2 at Malaysia while sectors 1 and 3 remained dry for around 5 laps at least, not knowing when or if the rest of the track was going to get wet and whether to hold out on drys or come in for intermediates. How on earth this sort of weather system isn't in the modern games I don't know. Even Grand Prix 4 had this feature, a game from 2002 no less.
But above all, they WORKED. The games have felt sloppy and careless lately, patch releases have felt further apart as if the team just wanted to move on and make the next one to get more money. And worst of all the attitude of the games have felt cheap and childish. I want the understated maturity of the earlier games back, where it was a serious, dangerous sport involving engineering and aerodynamics and not about internet memes and Youtube influencer liveries.
