Originally discovered this issue in a personal modpack of mine, I noticed that the overlay shown on screen when having the mekasuit from the Mekanism mod equipped will be offset by the same amount of pixel as that of the hotbar.
As such I went ahead and created a barebones instance of:

Minecraft 1.21.1
NeoForge 21.1.84
Mekanism 10.7.7 + Raised 4.0.1
https://mclo.gs/0ssE3yD

recorded a short clip of me recreation the issue in question for demonstration purposes.

hopefully it can be played in-browser as I otherwise have to rerecord it not using HEVC

If more info is needed, don't hesitate to ask. Could also reference this if it were needed to address to the Mekanism dev if it were more of a problem on their end