>>>>It seems to be some hide script on your navigator, try to open the levelextreme.com in incognito mode to prevent the issue and/or using other navigator for a while to see if the problem appears again. This will let you know what is going on.
>>>>Are you leaving opened the site for days and days? maybe that is also the problem, I never kept opened this site more than 2 consecutive days.
>>>
>>>I never close it. For years. It's a problem only recently. And my browser is Waterfox, where NoScript simply refuses to work.
>>
>>Why would you use Waterfox if NoScript won't work with it?
>
>А few months ago Firefox broke the interface to most of old add-ons, practically rewriting its API under different rules. All of a sudden nothing worked. Most of the refugees from FF camp claimed they became like a nanny state, taking care of the problems we didn't have and prescribing the desirable behavior. Waterfox is a fork of the project from the time that corner was turned. All of my old add-ons work. As for NoScript, I haven't really tried it yet, simply forgot :).

AFAICT the first few paragraphs of https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions explain why the change was made.

I only use 2 extensions for Firefox: NoScript and Enhancer for YouTube. When FF switched to WebExtensions it broke NoScript for a little while, but when it came back it was IMO better than ever. Enhancer was a Firefox suggestion after the switch, works fine with current FF and really civilizes the YT experience - zero ads.

Which extensions do you use which haven't been ported to current FF? Have the developers explained why they haven't been ported e.g. take too long to port, no longer technically possible to achieve the same functionality etc?