This can be caused by extensions that block ads like uBlock Origin. Try updating your filter lists.

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, DuckDuckGo PE, Disconnect, Ghostery, Privacy Badger, uBlock Origin), always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can try these steps in case of issues with webpages:

You can reload webpage(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Settings), click the padlock icon (Clear cookies and site data) for the domain in the selected tab.

"Remove the Cookies" for websites that cause problems:

• Settings -> Privacy & Security
  Cookies and Site Data: "Manage Data"

"Clear the Cache":

• Settings -> Privacy & Security
  Cookies and Site Data -> Clear Data -> [X] Cached Web Content -> Clear

• https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox
• https://support.mozilla.org/en-US/kb/how-clear-firefox-cache

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can check for issues with Enhanced Tracking Protection. Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content.

• click the shield icon for more detail and possibly disable the protection

You can check the Web Console for relevant-looking messages like blocked content.

• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/total-cookie-protection-and-website-breakage-faq
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

It's strange that it's always pushed to some add-on even though it was running with all the add-ons the whole time, just not even admitting the error that the updates were messed up.

MSN won't let me see the German version of their site, by default. I suppose I could trick it into doing so, but haven't invested the time and effort. However, when I visit MSN[dot]com with Firefox 121.0 (and uBlock Origin), I see what appears to be the correct display you referenced.

I do seem to recall having this sort of issue sometime in the past, but it has been a while. I fiddled with ad blockers, Firefox tracking protection, etc., and got it working.

Why should I mess around with any plugins if it's a bug from Mozilla because they can't program their updates correctly? I don't see it at all. Mozilla has been driving the FF further into the wall with every update for years and they don't even notice it and then what to do about it? No, why is everything OK is always the fault of the user, not the developer. The club is no longer sustainable.

even though it was running with all the add-ons the whole time

Websites are constantly changing which can cause conflict with extensions at any time. If you restart in Troubleshoot Mode with all extensions disabled, you will likely find that it works.

If you don't want to mess around with extensions, don't install them.

Yes, yes, the websites and their new settings are to blame if programmers from the FF are not able to program the updates sensibly. Tell me, how stupid do you think I am?

Well, what's going on here, doesn't Mozilla want to or what's the point?