This is most likely a discourse issue and not something that can be fixed by the devforum staff, it seems just to be terrible UX by discourse. I’d file a bug at discourse meta:
We likely won’t be able to prioritize a fix for this or follow up with Discourse ourselves since it is quite an edge case and a front-end-only quirk. Feel free to bring this up with Discourse yourself on the link above. Apologies for the inconvenience.