All tabs will have the same color

Starting with several previous versions of Firefox, instead of each tab having a different color, all tabs have the same color.

Also, if you have more than 50 tabs open, most of the tabs on the page that seem to be exchanging very little data at all times, such as exchange rates and stock charts, will be frozen.　Even if you try to open it from a new tab or bookmark, it will only show a reading mark all the time.

As a result of changing Firefox settings and turning on and off the add-on you are using, the above symptoms did not appear at all when this add-on was turned off.