[WPMU DEV Dashboard] Plugins not loading

On Saturday we rebooted our server for the first time in a couple of weeks.
When we restarted, we had two main issues:
1) create_function() was now deprecated (no update, using php 7.3.5)
2) our plugins would not load
We've tried everything we can think of to get them to reload.
It seems like something is blocking them.
Some of the posts suggest some sort of plugin list caching.
Others say to reinstall plugins. We originally added all of our plugins
simply by copying over source code to the plugins directory.
We are a multi-domain site.