Opened the server, was AFK for like 5 min, 2 ppl joined in the meantime, started moving, both of them got kicked due to desync. I dont even know how this is even possible...
After removing this mod everything was fixed.
Here is the desync report i got from one of the players, https://privatenextcloud.ddns.net/nextcloud/index.php/s/cQP4Rj58HKcarcP (Link valid till 1.Feb.25)

Thanks for the report! I will look it over ASAP and try to fix it. Apologies for the late response.

The issue should be fixed in the latest build (2.0.9) which is going live later today, sorry for the long delay in fixing it, it was hard to reproduce. If it still happens I've also added more logging so I can fix it faster.

Edit: Mod has been updated. It should work now.

The mod is now located on the original page at https://mods.factorio.com/mod/GUI_Unifyer again, you can safely move over from the Unified fork. I will keep it up to date there. I'm assuming it works for you now, if it doesn't, feel free to open a new issue there.