Even with no addons installed, the base UI can become corrupted. I highly recommend doing a full UI reset as described in the following support article:
Although, I do see TSM at the bottom of the auction window, so there is at least one addon installed.
Terise noticed it before me, but the tabs in your picture is showing tsm4, so if your add-ons are disabled there’s still data affecting the UI. Try renaming the folders and restarting the game.