You can inspect the website and detect a backdoor. It is not easy, but nobody would risk to be caught doing that. On the server side, we have no possibility of knowing what happens.
If you are interested in checking a completely different approach, you can look at Secrez https://github.com/secrez/secrez. It is a CLI secret manager that supports git repo for distribution. Using other packages in the suite, Secrez allows direct communication between local desktop accounts using SSL tunneling.
Disclosure: I wrote it.
Sometimes I have the impression that some entrepreneurs like to say that there is a bubble because so they can say: "Yes, he raised all that money, or had that big exit, but not because he is better than me, only because there is the bubble".