I will never, ever use /e/ browser as long as it is based on Chromium. There are several reasons why and they include Chromium relies on Google to add functionality and they won’t offer any alternative whatsoever. For example, they rely on Google to check and update extensions and for any cloud related stuff (obviously these are not counted as trackers). Now, this may be a matter of who you trust, but it is awkward to have as a goal to degoogle Android and at the same time use Chromium, even if it is a forked version.
This is not only a matter of trust or even how many trackers are included in the build, it goes beyond, expanding the power of Google on the internet, helping them to set de facto standards in the interest of Google that other browsers will need to just follow up because of overwhelming adoption.
Firefox can do everuthing Chromium does. I don’t want to be rude to /e/ but if Debian has no problems with Firefox in terms of openness, security and privacy I’ll go with their decision of including this browser as default instead of /e/'s alienating decision. In the end I don’t think /e/ can be convinced to change its default browser, that’s already decided. I just wanted to express my opinion.