I might have managed to fix the problem — since I did this, I haven’t had any crashes with FC26. I can’t guarantee it’ll work for BF6 as well, but you can give it a try.
Add the EA, EA Games, and Electronic Arts folders to your antivirus exclusions.
Right-click the EA App icon, select Properties → Compatibility, then check:
“Run this program in compatibility mode for Windows 8”
“Disable fullscreen optimizations”
“Run this program as an administrator”
Do the same for the BF6 executable.
Restart your PC and try launching the game.
Again, this isn’t a permanent fix and I can’t guarantee it’ll work for everyone — but for now, it’s been working for me after several days of issues.