why has messenger dissapeared from the watch

If you mean Facebook Messenger, Facebook no longer supports Messenger for Apple Watch. This was a decision they took. Apple doesn't own them and has no control over their apps.

Randall_2023 wrote:

Probably because Apple blocked Facebook tracking users every move.

Probably you are completely, wrong. Apple didn't block Facebook Messenger at all. Facebook chose to stop supporting Messenger on Apple Watch and they even went to the trouble to tell users support for the app would end. Again, something Apple didn't do or anything Apple had control over.

Messenger?

Did you mean Apple Messages?

or one if the Meta messengers like Facebook or Instagram?

Probably because Apple blocked Facebook tracking users every move.