I just updated my 2020 iPad Pro to iPadOS 16.1.1 (from 15.6), and now my entire document is in shambles because the Courier regular font that I was using is suddenly missing. It did occur to me that the font could have been removed from the OS in this update, but that strikes me as unlikely given how ubiquitous Courier is and since the font is still listed and correctly displayed in the font menu. Not sure what’s going on now, but I’m about ready to give up on the iPad app for a while.