Thanks for the extra details. Since you’ve already tried reinstalling, verifying the files, updating drivers, changing V-Sync switching to Borderless, and resetting Personal Settings 1, please also try these steps:
First, fully close FC 26 and the EA app. Then go to %localappdata%\EA SPORTS FC 26 and delete fcsetup, settings, and Umcache. After that, launch the game again and test one full match.
If the issue is still happening, please back up any local saves you need, then clear both Documents\EA Sports FC 26 and %localappdata%\EA SPORTS FC 26, restart the PC, and test again.
Please also check whether the game is changing your graphics settings on its own if you reset settings back to default. In some similar reports, settings such as Strand-Based Hair, Motion Blur, Cloth, Crowd, Grass, and Ambient Occlusion were switching back to heavier values. If you notice that, check this thread to see if you can use that workaround - LINK
Also worth testing:
- disable GPU Power Percent monitoring in MSI Afterburner (only if you use it )
- on Windows 11, turn off Hardware-Accelerated GPU Scheduling
If none of that helps, the next step would be a clean GPU driver install and then a clean boot test.