I perceive the new profile system more as a extended capability of the old profiles than completely new and different thing. Although for a typical user it probably seems like a new feature since previously the profiles were quite invisible.

With new profiles, each profile will have a profile group they belong to, which means roughly “these profiles are linked”. Profile data is stored in separate directories just as before, but the linked profiles can open browser instances of each other and they can have some information shared between them, such as shared preferences, which is stored separately from the profiles themselves. I don’t think it’s there yet, but I believe you could then also have a profile-1 to open new tab in profile-2 etc.

Different Firefox versions can’t share profiles in the same group, so release Firefox has its own group, Developer Edition has its own group etc. In addition, I believe this new profiles capability is limited to “standard” profiles only, i.e. those that are stored in the default location and/or are reachable via profile-manager. They cannot be used with profiles loaded from arbitrary directories via command-line flags.

Go to about:config and create a new number pref with name ui.prefersReducedMotion and set the value to 0. Afterwards that Firefox profile should use animations even if they are disabled on OS. Works on Windows at least.

Felix Mikolasch, data protection lawyer at noyb: “Mozilla has just bought into the narrative that the advertising industry has a right to track users by turning Firefox into an ad measurement tool. While Mozilla may have had good intentions, it is very unlikely that ‘privacy preserving attribution’ will replace cookies and other tracking tools. It is just a new, additional means of tracking users.”

Sigh… I cannot for the life of me figure how anyone could think that enabling PPA (even by default) means that advertising industry has somehow right to track folks. Like dude, the entire point of PPA is that advertisers could then get to know if/when their adverts are working without tracking people.

The argument that “It is just a new, additional means of tracking users” also doesn’t really make sense - even if we assume that this is new means of tracking. I mean, sure it technically is new addition, but it’s like infinity+1 is still infinity - it doesn’t make a difference. The magnitude of this one datapoint is about the same as addition of any new web api (I mean there are lots that shouldn’t exist - looking at you chromium… but that’s besides the point).

File a complaint over use of third-party cookies and actual tracking if you want to be useful - this complaint just makes you look like an idiot.