Why do texts and links disappear in Firefox?

I hope someone of you can help me further. I'm desperate.

I have been trying to locate the problem for two hours. Without success.

I'm currently using a new laptop and have installed Firefox, Opera and Avira. System is Windows 10 Pro.

Now it happens that various websites are displayed to me normally, but as soon as I log on to my account with my account, e.g. Disappear Article descriptions, links, etc. I log out and clear the cache, everything works again (without cache clearing it doesn't work either, so I have to clear it so that I can see the page correctly again, but if I then want to order something and log in again, parts of the page disappear).

I suspected that it might be a security setting, i.e. Deactivated AdBlock, deactivated Avira, deactivated Defender, etc. But nothing solved the problem. Among other things, I created a new profile for Firefox, but it does exactly the same thing. I do not know how to continue.

The laptop is brand new, about a week old and installed the Avira right after I switched it on. After that everything else, like Firefox, etc.

All updates are up to date.

maybe someone of you still has an idea what that could be. I'm thankful for every help.

PS: while I was writing this, I also tried Opera. There's exactly the same phenomenon. So a setting of Windows? If I try it on the MacBook or the old laptop, everything works perfectly.

Since it also happens with OPERA, it lies

either in your restrictive settings, which you have made equally on both (!) browsers (e.g. Blocking third-party cookies)
or any "ominous" additional programs that you have installed in WINDOWS that have anything to do with the layout of web content; can't actually be:-)
the specific settings within those ACCOUNTS that you control with the browsers. The problem only arises after LOGIN, right?

I prefer the 3rd)

Hm, good starting points. The joke is yes, about two days ago everything went perfectly. It's only been going crazy since yesterday. And in the meantime, I haven't installed anything new (other than the VLC player last weekend). I only surfed on the usual pages, so nothing unusual.

What just puzzles me is that it works on both the MacBook (Safari and Firefox) and the old laptop (Windows 10 Home, Firefox and Opera). Only now on the new laptop does it go around like this.

The thought that it might be due to my account came to me too, but since I didn't change anything… I checked it again, but everything was fine and as usual.

Is it then possibly on the sides themselves? So wrong programming, so that when I log in, the whole thing gets hiccups somewhere? Maybe a stupid thought, but it would at least be an explanation.

I found the solution to the riddle 🙄 you have to figure that out!

I noticed that some of the pages had a maintenance mode a few days ago… And, right, I've had the problem since then. What they changed: The pages can now be viewed in different languages. However, since it is mainly used in English-speaking countries, the content that is missing under the German view is displayed ONLY in the English view.

I usually surf the site in English, but since the maintenance mode, the website must have determined that I'm from Germany (IP?!) and as soon as I log in with my account, the site will, even if I have nothing changed in my settings, automatically displayed in German, but where the content is not available. I have now switched to English manually and lo and behold, everything is back.

Nevertheless thanks for the help!

So then: do a system restore to a backup point from 3 days ago or before and then check those accounts display quality. It could also help to eliminate all files and settings from and for those accounts that are on the local windows and then upload them again. I assume that certain files were not installed but only copied into the storage locations. Quite vague, since you don't write which WEB sites are; not everyone should know where you are active:-)

Thank you for your help. I'm just realizing I answered myself up there instead of you.

I found the answer to the riddle. It's the language setting, and I haven't checked all of the pages yet, but two did.

All of this also occurred on eBay, for example, when I called up an English page via the German portal. When I got back to .com, everything worked again.

I do not know whether it is Windows, browser or account, but I have to see if I can somehow adjust it so that I can see the English texts again on the German pages. Funny thing, but at least it works again. That is the main thing.

In any case, thanks again for your help.