WordPress 5.8 breaks site on upgrade

Hi WP folks,

I want to preface this question by saying I have indeed read the master list of this WordPress 5.8 check list. I still have some questions though and some explanations, as well as things I hope to have explained to me.

So two times I have attempted to upgrade the WordPress version to 5.8, as my dashboard has told me I’m not running the latest version. Update now.
BTW, I’m going to include some screen shots so people can see some plugins I have — whether active or not — and they might be able to tell me which if any are problematic.

I used to use Jetpack, and would like to again, but it requires an update which in turn breaks the site.

For starters, I’ll just say ALL of the PHP files start trying to be downloaded, rather than run in the browser. So I don’t know if this damages something in the .htaccess file (a good bet, IMO) like the list suggests, or if it’s something else or both things.
I can’t even log into the host provider to do it. The PHPs to hit WP in the console also attempt to download PHPs as files to save, not run.

When I tried to run the healthcheck test without plugings, I get this error message:

<em>"Loopback request -- The loopback request to your site failed, this may prevent WP_Cron from working, along with theme and plugin editors.
Error encountered: (0) cURL error 28: Operation timed out after 10001 milliseconds with 0 bytes received"</em>

It then instructs me to run individual plug-ins. Maybe the genesis of the issue is here?

So then I ran the individual plugin check and all but this one (Social Feeder The loopback request to your site failed, this may prevent WP_Cron from working, along with theme and plugin editors.
Error encountered: (0) cURL error 28: Operation timed out after 10000 milliseconds with 0 bytes received) ran successfully.

I think I will deactivate and remove that plugin for now.

Ok, during the course of this I have activated some and updated all plug-ins. I will likely rename the mu-plugins folder as suggested on the master list and check things.

I’m attaching the various screen shots and still welcome any and all feedback.
Ok, I’ve got about 7-8 screen shots but don’t see a way to upload or attach them. Please advise.

Thanks,

redraider90

The page I need help with: [log in to see the link]