Your profile mentions clean code and SOLID architecture. Especially the latter is weird – SOLID is not an architecture. That may explain also the rest of your, insightful, article. Almost none of the points you mention can be blamed on Firebase, but plainly on the lack of proper development: no architecture, no design reviews, no automated testing. It reads as if you are the carpenter who blames the hammer when hitting himself on the thumb.

We all learn new things every day, so it’s not a big issue in that sense, but I’d suggest you take a step back and look at your way of working rather than just the tools.