When several reply comment boxes are open, clicking on formatting (e.g. bold or italic) icon applies a markup tag - but to a comment box above!
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I noticed this too
Kbin is super much in alpha dev still! Perhpas tryout Lemmy, thats a little further along (our instance is on https://u.fail)
I try but fail. Tried to register - entered the data and clicked “Register” → endless waiting. The same when I try to log in.