Why is my Apple Watch SE 2022 showing 'Syncing Data' after a long period of inactivity?

Why is my Apple Watch SE 2022 gps and cellular saying syncing data in Apple Watch app after not using it for a while and showing syncing symbol on my Apple Watch? Now it’s finished doing it it’s the same as before and no different to before it started syncing

[Re-Titled by Moderator]