I think I saw a YouTube video where some developer said that Apple requires you to use latest version of Xcode, that version has a minimum SDK (I think iOS 15) and he was complaining he couldn't update his iOS 12 targetting app anymore.
I believe Apple makes it difficult, but not impossible. At the end of the day, these things are specified in text files that can be edited, regardless of what options the GUI gives you. Definitely shame on Apple for trying to nudge developers to give up on older phones, but it aligns with their desire to keep their customers buying new phones.
