My MBP, 2015 was restored and now it has El Capitan on it. Is that the latest it will take? I had beta 12 running on it at one point. When I go into pref and select update it tells me there are none.
"macOS Monterey is compatible with these computers
MacBook Pro (Retina, 15-inch, Mid 2015)
MacBook Pro (Retina, 13-inch, Early 2015)" https://support.apple.com/en-us/103260