It's internal. They are becoming irrelevant (their browser market share have been shrinking for years now), so they are jumping all the new hype trends now. They literally just became an ad company. We have Google, Apple, Brave and Mozilla all being an ad companies that produce browsers.
Microsoft dominated with IE back in the day for the same reason Chrome and Safari are the dominant choices. People don't tend to change the default if it works okay enough. Firefox dropped heavily years ago as the market was saturated with other new choices already installed on mobile and Chromebooks, but recent numbers are about the same as they have been for a while. Maybe even still growing, as all the numbers I find are percentages, and there's no doubt we've had an explosion of device use.
Someday I'll just switch to Waterfox or some firefox fork that doesn't have this shit baked in. Although, I would much rather have an alternative written from a new browser engine in Rust, Go, or at least something more sane and as performant than C / C++.