Found a "workaround" that's still kinda annoying, but at least makes it usable again temporarily. set page zoom to something really high like between 200-400% zoom, then reset back to 100% zoom and the text input box will reset to the bottom. its temporary though as soon as you send a reply then it goes haywire again, so after every response you send just set zoom to 200+% and then back to 100%.
Stupid workaround but we do what we must...