Why can't I send an email of a Preview file from my Mac?

You need to have Apple Mail as your default Mail application, and when that is true, I have no issue clicking Share : Mail and having the Preview document attached to an outgoing email compose window.

I have apple nail as my default and it still doesn’t work? It used to work until Monterey update - now is not in sharing menu at all

Did it work before?

Only thng I can think of is...

Open Terminal and run each of these one at a time

/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

Log out & back in.

It shows in Preview on my iMac running Monterey 12.7.2.

Try booting into Safe Mode then restart normally. Sometimes that will fix anomalies.

Use safe mode on your Mac - Apple Support

It shouldn't be. Try restarting your Mac.