After I noticed Firefox has removed the Pocket branding but kept the Pocket stories, I also noticed the settings screen on the homepage no longer lets you disable sponsored stories or links.
Firefox 115:
Firefox 139:
You can still remove these advertisements, but you have to leave the homepage and dig through the settings to find that option.
Paid by who
Mozilla Corporation, who gets more than 80% of its funds from Google, around $500 millions, who does that to ensure Google search remains the default and to avoid antitrust issue if Chrome because even more dominant.
Firefox forks will likely not be able to secure such funding and pay the engineers required to further develop a web browser fully independent of Chromium.