Admin subdomain of network: [an error occurred while processing this directive]

I’m having trouble with the old “[an error occurred while processing this directive]” error, but it’s only in certain scenarios. It’s only occurring on certain sites in my network and only when I try to visit the dashboard. Some subdomains work, some don’t. All use the same theme and both are accessible on the frontend. These are sites that have worked for years, but not are getting the error. The only major change has been updating PHP to 7.4

Things I’ve tried:

• Using that recursive script to change file permissions
• Removing <!–# comments
• Deactivating all plugins by renaming the plugins directory
• Wiping out the .htaccess file so that only WordPress network entries remain
• Ensuring that the subdomains are specifically defined on Bluehost (instead of just being covered under a wildcard)

Anybody have any bright ideas of things I could try? I’m at a loss at this point…