Recently, I decided to 'start over' with my Firefox profile due to some issues with too many tabs (I'm that personality type that leaves everything open). As a result, I started over and the first thing I did was update firefox and implement the js and extensions from ffprofile. I also installed Firefox's multi-account container.

However, I've noticed that certain websites break, but there's no discernible explanation for why they may break. I think I have a fairly strong understanding as to why some of the websites may potentially break, but I don't really know the best way to troubleshoot them.

In my example, plex.tv . With CanvasBlocker, uBlock and uMatrix (there may be other extensions that are the culprit but I haven't delved too deep). When I try to load the sign-in page for Plex, I just get a blank modal popup.

While writing this, I thought about how I can go about this: making sure all my extensions are set not to run in private windows, and then slowly adding extensions and enabling them until something breaks.

My primary question is: what do you do, and how can someone approach this in a methodical, easier way?

A secondary question I have is, related to these are, is there a recommend training video that goes into tools like CanvasBlocker and the browser DOM to show how to troubleshoot an issue like this? Or rather, are there other extensions someone can use to troubleshoot this scenario?

My reason for asking these questions is, as someone that has slowly started to increase my privacy (albeit on a very basic level, and not as extreme as others here), I have the opportunity to teach and influence a lot of people who come into my field cyber-security, and I'd like to do things right. I do not want to give people solutions that are broken and I realize, the barrier to entry is high if your goal is to understand what breaks and how at a very low level. If I got flustered with a simple website, I imagine the average person would just throw their hands up. I'm looking to be comfortable with these concepts enough to prevent that.