What's wrong with AGPL that doesn't fit with our ideas?

We were on the MIT first and got into a situation where a large corporation wanted to take our code and resell it to tens of thousands of their customers and they made it clear they didn't want to contribute anything back to our project whatsoever.

We are a two person team putting our own time and savings into this and it could have instantly killed the project and the chance of becoming sustainable.

We changed the license and that was a simple way to stop them without changing our principles/ideas. Could have gone proprietary too at that stage but we didn't.

Everything is clearly explained here https://plausible.io/blog/open-source-licenses