I've been reporting issue about font rendering in the past, recently someone else also reported something similar (can't find the post though)

I have this alias which draws an unicode character to a picture window, but sometimes it wasn't drawn correctly/entirely.

After a long debug, I've figured it out, it was whenever i joined a particular channel with a particular topic, which had a particular unicode character in the topic.

The first unicode character is drawn with "drawtext -rn @sbm 0 "Verdana" 14 770 400 $chr(9650)"

I'm realizing while writing this that verdana does not have the character, so font linking is occuring I suppose.

Once I join a channel with "PᗣᗧMᗣN" in its topic, the character drawn with drawtext is glitched, and this happens while the window is open with the correct drawing, I don't even need to close/reopen.

This is on windows 10 and mIRC 7.61, Wims, which helped with this cannot reproduce on windows 7.

I hope this helps resolving the various issue with font linking and font rendering, I can make a video if needed.

Thanks for your bug report. This and related issues have indeed been discussed before eg. here, here, here, here. Please see my replies in those threads.