1. I had several Qt for Android versions installed, with corresponding auto-generated kits.
2. I removed one of the Qt versions.
3. The corresponding kit would now get a different Qt version assigned to it instead.
4. In my case this was a desktop Qt, so the kit had a red flag due to the fact that the selected compiler could not be used together with the Qt version or something like that.
5. Since the kit was auto-generated, it was impossible for me to manually remove it.