UPDATE:
I love the irony that JavaScript needs to be enable to access these forums...
I have been working on this issue and so far the only current workarounds / solutions are:
1) Reinstall the OS BUT I have not tested and is time consuming...
2) Use Firefox ( My preferred solution while I wait for Apple to release a fix/update. )
3) Use Chrome ( I avoid due to security concerns and data harvesting by the big G. )
4) Install the Apple Developer preview of Safari 14.2 ( https://developer.apple.com/safari/technology-preview/ ) NOTE this is a preview that coexists with the current version of Safari ). Since it is not an official release there are risks. I have tested and it works perfectly opening problem sites.
Some research on the net points to an issue with a file named libwebrtc.dylib. With 14.1 it has the date March 1 2021, the version with the 14.2 Preview is March 30 2021... Due to strict OS integrity controls by Apple (SIP) one cannot simply delete the updated version of Safari and reinstall the previous version from a TimeMachine backup. The same is true for other System files like libwebrtc.dylib . I may test a file swap by disabling SIP, swap the file and reenable SIP but that is a risky test and I need time in case a full OS rebuild is needed.
So far Firefox is the simplest solution.
Prost!