In short it was not a bug
.
Application Davinci Resolve: trusted and it becomes a pass_thrue for the antivirus.
Believe me, these advises like "Update your drivers. Turn off you Anti-virus. Wash your hands before editing. Reboot, restart, reinstall, exit from your room and enter again. Sleep 8 hours a day" helps in 0.00001% of cases (for some rare newbies)
In my case when I write to support usually it's a software bug. How the hell anti-virus can affect rendering of 4k50p by GPU? Of course it's turned off for mp4 and mov files
Antivirus checks only executable files and it doesn't use GPU for that)) All supports making everything not to help but to get rid of annoying customer