We're using Steam remote play to speedrun together, and we're on the Legacy version. We've tried several things to stop this but to no avail. When we were playing locally this didn't happen, so what can we do?

This is a glitch called “text storage”. This and other glitches are caused by exiting to map while talking to elder kettle. This can cause glitches like the apple guy just not talking to you at all or what you mentioned.

Got it. Thank you!