I'm thinking about switching to bitwarden cloud solution but how does it have a free plan?

So I was selfhosting vaultwarden for a while but I kept it on the local network, didn't want to open no ports on my network for security reasons and I tried vpn and IDK why but I found it unreliable maybe I did something wrong with my setup. BUT lately I found myself needing access to it from outside my local network, so I was looking for alternatives and only recently have I learned that bitwarden has a free plan, and a pretty generous one, you get all the features you really need. My question here is, how can something like this be for free, like as far as I know if something is free you are the product. Am I right to be suspicious of this plan or Am I just paranoid hahahaha