Also be aware that if the title of the tab you are in is in italics, you can double click the tab - then it will become 'normal' font text and will NOT be replaced. Making a change in a file will also change the title from italics to normal and stop it being replaced in the same way. Tabs were driving me insane till I worked this out. Dont know if there's a keyboard shortcut for the double click?

I just had a similar issue with Xcode 16 and iOS 18. Turns out I had updated the main app 'deployment target' to 18 but the widget to 18.1. You could install the app but the widget was missing from the widget search. I know olvrptz said his widget shows up on is simulator so this may not have been his issue, but just one to check in case it's yours.