Plugins are not staying disabled across browser restarts.
I am disabling plugins in about:plugins. Recently I noticed that all plugins are enabled. Disabling seems to work, but after a browser restart all plugins are enabled again. procmon.exe suggests that there are changes written to pluginreg.dat when disabling a plugin. Deleting pluginreg.dat or addons.sqlite (and disabling again) didn't help either.
This behavior is not limited to specific plugins, but all of them that I have installed.
Moambuepyre
Opaite Mbohovái (2)
tluzat, i have the same issue every now and then & didn't find any real solution for it yet either...
looking at your extensions, i don't see much similarities (except adblock) to my setup. i'm mainly using the aurora build, can't remember exactly for how long this ongoing but it occurred at least since the 19a2 builds. clearing the various plugin related files within the profile folder didn't bring success for me either :-/
as a workaround i can launch firefox into safemode, then from within it select "restart with addons disabled" and after entering safe mode again disable plugins - their state will then be usually remembered after a normal restart of the browser.
i've filed bug #839728 for this issue. as a workaround in the meantime you can try to close all other tabs before you enable/disable plugins in the addons manager...