This may be a plugin or theme conflict. Please attempt to disable all plugins, and switch to the default Twenty Twenty theme. If the problem goes away, enable them one by one to identify the source of the problem.
If you can install plugins, install Health Check. On the troubleshooting tab, you can click the button to disable all plugins and change the theme for you, while you’re still logged in, without affecting normal visitors to your site.
Thanks. I installed health check and discovered that my PHP was 7.3 instead of 7.4 so I updated that. Unfortunately, I wasn’t able to figure out if a specific plugin was causing the problems using their troubleshooting because I think the plugin conflicts were specific to the theme.
I then ran a PHP compatibility checker plugin and discovered that two plugins (get your guide, and booking.com) had issues. I deleted both and now everything seems to be working!