Seems like Firefox's built-in protection is mostly about 3rd-party trackers? Even the description for "Tracking content" (the not-obviously-3rd-party category)

Seems like Firefox's built-in protection is mostly about 3rd-party trackers? Even the description for "Tracking content" (the not-obviously-3rd-party category) talks about "external ads, videos, and other content with tracking code from other companies. For example, a website may embed a video from a video platform". And this category is not blocked by default, only in strict mode.