Here are a couple:

1. The inability to set a specific page for new tabs to open on. That is ridiculous.

2. The mobile version sucks, specifically because bookmarks are buried under an absurd number of menu levels. And they're also broken up (without user approval or any way to stop it) into "mobile" and "desktop" bookmarks. WHY? The entire point of syncing is to have them all the same.

I want to like Firefox. I went back to Firefox for the first time in decades last year and gave it up after a couple months because #2 was that annoying. So brain-dead.

Oh yeah, and another one was that "never remember history" does, in fact, remember history. What Firefox really does is "stop adding to history." And the bug report on it resulted in several YEARS of debate over how to "fix" it. The latest I saw is that they're actually NOT going to fix it, but rather add more text (somewhere) to say basically, "This doesn't do what you think it's going to do."

If fixing a defect like that requires years of committee back-and-forth, the product is finished.