I have "Beta channels" set to *disabled* in the config of GOG Galaxy.

Despite this, version 0.9.026.m022 is installed. That's a "development" branch, not a "main" branch. Galaxy needs to be updated to correctly distinguish between development versions and main versions.

This isn't a problem for me, but might be unexpected behavior for many.

Admittedly, this and the more recent update are patches not major updates, but I'm not sure this is expected behavior.

It seems that GoG is behind on versions because of the publisher, not because of GoG. The Miju Games website lists the Steam forums as the place to go for support (which itself tells a tale). There's a thread on the Steam forums where Miju promised a couple of years ago to keep GoG up-to-date with Steam. I've bumped the thread.