I couldn't figure out how to downgrade Safari from 15 to 14 on Big Sur, so I ended up reinstalling 11.6 by downloading the Full Installer linked here: https://mrmacintosh.com/macos-big-sur-full-installer-database-download-directly-from-apple/
Be warned that the full installer is like 12 gb.
Be warned that the full installer is like 12 gb.