Sorry about this experience. I hope the issue has been resolved by now. If not, I recommend resetting Illustrator's preferences to see if that helps. Before doing so, please remember to back up any customized settings, such as workspaces and presets. You can find the steps to reset preferences here: link.
That does look strange. Would you mind confirming the version OS/Illustrator running Illustrator under a different administrator account (Windows / macOS) and checking if it continues behaving this way?
If yes, try the following steps and share your observations:
- Close all Adobe applications.
- Rename the UXP folder to UXP.old from the following location:
(Windows) Navigate to C:\Program Files\Common Files\Adobe\UXP
(macOS) Navigate to Macintosh HD/Library/Application Support/Adobe/UXP