

False.
The ad attribution system was proposed but never implemented due to user outcry.
Some telemetry has been a part of Firefox for quite some time now; but it has always been privacy respecting and they self-host all of it. In general you can easily turn most, if not all of it off. The telemetry thing has been around since before they even started seriously fast-cadence releases. Some of my memories of this date back to the Firefox 34 days even. None of the telemetry collected is mandatory, and it can be shut off in preferences as well as through advanced config; which is what most forks do if they don’t specifically rip the code out. You should read their source code sometime; it’s quite interesting.
I will however agree that Brave is way more intrusive than any misstep made by Mozilla in developing Firefox.
There’s something you need to know about the “anti-features” flags on F-Droid.
They’re too “greedy” and widely defined. What you really need to do is examine the app and how the developer might use said “Anti-Feature”. Not all internet access and telemetry is an anti-feature, and neither is reliance on a “third party service” where you can simply configure your app to use your own self-hosted server instance.
An app having no “Anti-Features” flag on F-Droid is absolutely not an informative indicator that it respects your privacy. Merely, it indicates common privacy foot-guns may not be present.
Frequently F-Droid also is far too opinionated in it’s application of the anti-feature flags; giving developers no reason or chances to appeal or change the decisions. It does not matter if the anti-feature flag is mis-applied in any specific situation; nor does it matter if the developer shouldn’t be getting an anti-feature label because they have everything open sourced and it’s clear to see there is no anti-feature there.