Version Change Prompt without Updating?

[Crabmann]

So I'm playing modded singleplayer and I had to restart the game, and it prompted me when loading into the world that the version had changed, but I went back out and looked and it hasn't, I'm still in 1.20.4, BUT some mods aren't working like they were before, namely Freedom Units works with HUD Clock but not on actual items anymore. I haven't noticed anything else that's broken, but I'm very confused why it's happening.

[Maelstrom]

I believe once a stable version is released (like 1.21.0 stable) there is a notice to update if you play on an older version (like 1.20.x).   No actual update is made until you initiate it but mods may break in the older version.