Since upgrading to 15.0 (24A335) Pages is no longer opening Word documents docx (discussions.apple.com)

I found the right answer to the problem (at least for me). @tinodj has been right, but no proper execution.

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user

sudo /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -seed -lint -r -f -v -dump -domain local -domain system -domain user -domain network

killall Dock