Installing Bigsur on an old imac (2011). Working fine

iMac,Mac

Installing Bigsur on an old imac 12,1 (mid 2011)
Upgrade hard disk to SSD (WD250)
Upgraded RAM from 4GB to 12GB
Everything works fine, but screen recording doesn’t work.
Watching Youtube, google office, chrome, Edege, Safari is fine. Video editing is a pain