But then I remembered how the last time I went to build an internal web extension I couldn't even deploy to Firefox without uploading that internal extension to Mozilla. Left a really bad taste in my mouth.
Meanwhile deploying an internal web extension to Chrome was pretty straightforward, signing the extension was just another step in the CI process.
On Firefox side of things, I prefer to upload my source code than to get blocked commonly with ambiguous or not clear reasons.
Honestly, if you think about it, all browser extension could be open sourced, it can certainly improve trust, and, they run on the client side anyway.
Just look on the hn posts this year, there has been lots of people complaining about the Chrome review process taking more than 3 weeks, and rejections without clear reasons.
I had a similar experience with Firefox and I think for some, it's hard to justify that extra effort (from development all the way to publishing) given the current market share of Chrome in comparison.