Apple Watch does not update during pairing.

I've got iPhone SE (1st gen) and Apple Watch Series 1. Current IOS is 13.4.1. I didn't use my Apple Watch for a long time and then decided to activate them again. But during the pairing process Watch app asks the permission to update WatchOS and after that there is this message: "To update the software on your Apple Watch, you first need to update the software on your iPhone." But my current IOS is up to date. Is there a reason why this problem keeps occurring?

P.S. As far as I know all those devices still support lates OS updates.

Yes, I tried reinstalling the app, restarting both iPhone and Apple Watch.