Is there anything useful usually in those fw updates?
Probably some dubiously useful features such as a nicer web UI (I never use it anyway), some utterly useless features like "scanning to Dropbox/GDrive", or most probably now some "AI assistant" that tells you how to switch cartridges.
Not in my experience. No user visible changes.
There might be some fixes to bugs
That tool appears to be getting the firmware from brother servers. They have removed the old firmware as of more than a year ago (this issue is not new)