Is there a way to auto upgrade RoS when single packages are installed instead of the main package? It seems like "system package update" works only when RoS main package is installed?

It should work. Normally I upgrade from WinBox, but I just did "/system package update install" on 6.46beta6 with individual packages and it worked correctly, downloaded packages, rebooted and it has 6.46beta16 now.

Strange, it does not seem to work from 6.45.2 to 6.45.3. Actually it does not even detect there is a 6.45.3 version available. It comes with a "System is already up to date" message.

PS: Using CLI or Winbox, still the same message in quite a few different mikrotik systems.

And does the system see it as available (/system package update check-for-updates)? Mine doesn't. I've seen 6.45.3 mentioned, but not by MikroTik employee, so maybe the user just got lucky and hit the first mirror that got it.

6.45.3 was posted 3 days ago so mirrors should be in sync by now. /system package update check-for-updates comes with the same message also.

It is actually posted in main site also as the current release

https://mikrotik.com/download

Interesting, I'm only aware of this post from today and I missed the date. But no official announcement, or I'm going blind.

No, I don't think there was any announcement at all unless I missed it also.

Yeah, it also showed on the feed (https://mikrotik.com/download.rss) only today afternoon.