I do have same GPU as urs(same VRAM as well)yet not CPU(i5-11300h)the game runs fine for me after spent so much time literally trying everything. Here's the workaround stuff I did and it gone fine with the game ever since regardless the mode if it was Rivals/fut champ etc...
Graphic settings:
All low/off expect grass on medium(for my preference).
Display settings:
Keep frame rate lock to 60 and Vsync on. Resolution: 1600x900.
Render scale: 90
The rest are the default settings.
U won't get second half bug during a game. However, if u quit a match or the first match end, while getting back to the menus, fps will drop like it does between halfs but it ain't a big deal since u ain't in a match. In this case what u gotta do is exit UT. Fps will get back to normal. If it ain't, go to game settings(menu before game settings)check if fps back to normal. If it ain't. The last part is to reduce resolution to 720p from game settings(outside UT). U will notice fps gets back to normal. Then set it back to 1600x900 again after u see fps got back to normal again. One of em will work for u. After that u won't get that bug and u will play all ur games without any issues till u launch the game again with first match/quit a match again.