Accessibility icon does not support semi-transparent pixel

Please provide an example pack where this is shown off.

does the exported format support transparencey?

In 1.18.2 and 22w19a.

Requesting ownership of this issue, as the original owner's account is deleted.

Is the language button affected and if so does a dedicated ticket exist for it?

Cannot reproduce in 24w09a - a test resource pack is attached. I'm 99% sure this issue was fixed in 23w31a, in which the UI texture split happened and the accessibility button texture was changed such that it became composed of an icon laid over the usual button texture rather than a whole modified button texture in itself.

I can confirm that this is fixed in 23w31a: