Sorry for bad English. Auto translation. In RaceRoom Racing Experience I often get turned around in corners. The rear of the car is carried forward. I also play in AC and ACC. There such a problem is not. Maybe it can be corrected by car settings? What kind? At the link video (30 seconds) what are the settings of the car in the game. https://www.twitch.tv/videos/1929824921
make a clip of you driving with inputs showed (bind button for that) dont make any changes to car setup
Looks like theres one spin, seems to be caused by too much downshift, if theres more lemme know. Other than that, dont downshift to first gear so much and upshift earlier
If you want a more stable car, you can soften the rear suspension (springs, dampers, ARB) and/or stiffen the front suspension, increase differential preload, you can also increase rear wing. If the car is unstable under braking, increase "Engine braking reduction" (i.e. you'll get less engine braking).
Yup, this seems to be a driving input issue and nothing related to setup. Avoid first gear apart from starting a race as you don´t need it - in a real road car 1st is very rarely used when the car is moving. The Z4 can also be unstable downshifting to second so try another car where the gap between ratios of 2nd and 3rd gear is lower (cars where you can set the gear ratios are better) or do as @Maskerader suggested and put the engine brake reduction up to 20 and then reduce it click by click till you have a balance between too much understeer and the car spinning out from the rear. A good way to test if it is you or the car is to do a lap only using one gear e.g. 3rd gear. I know it will be slow on the straights but if it is controllable under braking then the issue is over aggressive downshifting, which destabilises the car.
Don't know about Z4, but in Bentley Evo I downshift pretty aggressively because it helps rotating the car on turn in and I never had a problem with it. Usually default setups in RR are quite stable on braking.