When I'm logged in and trying to change settings on a few installed and activated plugins (Autoptimize and WooCommerce) I'm seeing data which isn't coming from the WordPress DB or files.
For this example, in WooCommerce, I've searched the DB for %email@example.com% as well as the files. Both return zero results. I've also deleted cookies and cleared the (Chrome) browser cache (same bad data shows up in Edge too), Autoptimize and Varnish. (I've also paused Cloudflare so everything should be coming from Dreamhost.) I've also tried to make changes via incognito mode but the same bad data is showing up.
The DB contains an entirely different email address and when I try to update it in the WP backend it says "updated" and shows updated but when I reload the page it pulls the bad email address again.
Another possible symptom is that some plugins aren't de-activating / re-activating properly and I have to go into the wp_options table and add the plugin back into the active_plugins row.
I did try de-activating nearly all my plugins but nothing seemed to make a difference. I say nearly because it's a live site with active users and some of those plugins when de-activated will make the site appear broken.
I'm fresh out of ideas in finding out where this bad data is hiding and why WP isn't pulling the correct data from the DB.
Hoping someone else here might have something else I can try.