Every single company I've ever worked for was crushed by the unreliability of mongo. They're ultra-expensive consulting is also a ripoff - in one case the guy came, suggested a bunch of stuff w.r.t. changing up our queries and indexes, left, then a day later the database exploded and we had to roll back everything he suggested. We tried again piecemeal, which eventually lead to the same thing happening again. Eventually spending the cash to train the engineers and admins to be able to do the tuning ourselves - which ended up being completely different than the garbage the consultant suggested. Let me emphasize that this consultant was from the MongoDB company - not some third party. Completely incompetent company at all levels.
Mongodb exists to extort money from idiots on their cloud offering where costs balloon out of control. It was easily 40% of our monthly infrastructure bill and what we got out of it definitely did not reflect that.
We refused to pay them. Don't ever give Atlas money.