Sorry for the late reply, got distracted and have been trying to reproduce the problem in a fresh project. I haven't been able to do it in the about screen like my original example, likely due to how many changes I've made to it, but I have been to get it to happen in dialogue. This is in a fully updated 'release' version of Ren'Py btw.
Just add your shaders folder to a fresh project, add a default textshader, and give the default hyperlink style the shader:
define config.default_textshader = "typewriter"
style hyperlink_text:
properties gui.text_properties("hyperlink", accent=True)
hover_underline True
textshader "HighlightSimple:#ffffff"
label start:
"{a=https://makevisualnovels.itch.io/text-pack}Text Shaders link{/a} is something else to test."
I can send you a copy of my project if you are curious to see the initial issue as well, but it would need to be via Discord or something. Let me know.
