Modern UI without Embeddium (max GUI Scale: 3):

Modern UI with Embeddium (max GUI Scale: 2):

Embeddium without Modern UI (max GUI Scale: 3):

Expected: max GUI Scle = 3 with mui and embeddium

In some computers, it may cause huge inconvenience to users who is more used to 3 under 2.

Solution is to edit the GUI Scale in options.txt manually.

Maybe related to MUI's MixinWindow

Rubidium has this issue too

The situation remains the same, it's not fixed

Are you testing using the build from that commit? There hasn't been a release yet. On my end the maximum GUI scale is now the same for both (4), where it was previously 2.

It's reverted by Rubidium Extra lmao
https://github.com/dima-dencep/rubidium-extra/blob/1.16.x/stable/src/main/java/me/flashyreese/mods/sodiumextra/mixin/sodium/gui_scale/MixinSliderControl.java

Fixed in my fork