I have a website that was working OK until this weekend. Today I noticed that a number of browsers lost the ability to scroll the content vertically. The only modifications done to the server or the code last week were the recommended update/upgrades. My website uses PHP 7.3 + MariaDb 10.4 + some small JS scripts (jquery-3.4.1.min.js). It is located on a (virtual) Ubuntu 18.04 LTS Apache2 webserver (HTTPS) with 5 GB memory.
I have tested the website on a number of browsers; Firefox on Ubuntu/Deb10 is always OK, Chromium on Debian is also OK.
Chromium on Ubuntu, Vivaldi and Google Chrome on Ubuntu/Deb10 have scrolling problems (all these browsers are the current, stable version).
Win10 with Google Chrome or Edge gave the same problem.
Finally, I opened my website in a working browser, downloaded and copied the page source to a text (.html) file. Opening this file in any or all of the mentioned browsers was OK, scrolling worked perfectly. Testing with an old version of Google Chrome (chrome64_68.0.3440.84) was also OK, no problems.
I am at a total loss on where to start looking for the root of this behavior, is it my web-server or is it a Chrome problem? If more details are needed, please ask and I will try to add these to my question.