Welcome, @chk18!
You’ll need to go into Safari’s preferences and re-enable it under Extentions.
If it’s not there, you may need to rebuild launch services using the following command - or use the maintenance function in Onyx for macOS.
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user