Trello started filling the title of new cards in the list interface with a Trello card URL. I believe it's been the same link the entire time, but I'm not certain. If I press enter it becomes a shortcut to the linked card instead of a proper card.
This happens every time I create a new card. The cursor is after the URL so if I type the intended card name as normal it appends the URL. Regardless, I have to go back and delete the URL every time I create a card.
This started happening last week. Before then I didn't even know it was possible to set the title to a URL to turn it into a shortcut to a web page or Trello card.
It has stopped twice, but only for a few minutes.
I'm using Trello on an up to date version of Firefox (Firefox has actually gotten an update since the problem started) on an older iMac running Mac OS Siera. I was only running one Firefox Extension, but I disabled that on day one. I was also using 2 Trello Power-Ups, neither of them remotely new, I disabled those on day one also. I am using some automations, but they're all at least 6 months old and don't have anything to do with naming cards, creating cards, or creating links to cards (they're all about changing due dates when I check a card as complete, sorting lists, and moving cards based on their due date).