Add-on Manager checkboxes select more than one

Question

Is this a feature or a bug?

I have a fresh install of EE 3.5.15 (and have noticed this on other installs, thus my test on the fresh version). If I'm in the CMS on a page with checkboxes, such as the add-on manager. I click one checkbox in the middle of the row and several above it are also activated. It's not all above and it's not the same # of boxes above each time. And after you uncheck everything you are then able to check just a single box if it happened to be included in the initial auto selection.

Answer 1

The same happens here. Every list with checkboxes, like the list of a field set. Meanwhile I am used to press CTRL and then click the checkbox. That only checks that checkbox. I have no idea why this happens.