Automatic joining of marks with attributes

Oh yeah, now I see what you mean. Depending on have you selected/focused on the editor and what character you press (sometimes ‘m’ works, sometimes say ‘f’) it sometimes keeps the attributes, sometimes not in Firefox. But it still does fail similar to Chrome and Safari.

What a nightmare. But is there any way of detecting when these things happen?

I reduced the example into single html file https://teemukoivisto.github.io/prosemirror-weird-replace-step/