What happened?

I was fixin an incompatibily with bclib in my mod and noticed it.
My mod does some implementations to the AnvilScreen via mixins and there is method override conflict i was fixing.
At the moment i sudenlly resized minecraft's window and saw this:

Two button appeared. There was nothing before i did it.
I've never played with this mod and i do not know does these buttons are used in some case or not, but it is sure a bug cause in my case they does nothing and appeared after resizeing window.
I've meet this bug on 3.0.14-1.20.1 and desided to make sure the lates version was installed and found out that there is 3.30.1 published, i tested again on 3.30.1-1.20.4 and bug was there too.

looks like subInit method is called on resize not on init

BCLib

3.30.1 & 3.0.14

Fabric API

0.92.1

Fabric Loader

0.15.3

Minecraft

1.20.4

Relevant log output

No response

Other Mods

Almost perfectly clear mod list i was using on 1.20.4:
- ClothConfig 13.0.121
- fapi 0.92.1
- ModMenu 9.0.0
(and bclib ofc)