You sure you didn’t buy a 5600X? It was released in November 2020.

If not, it could be a 3600X.

Memory is a funny thing, don't beat yourself up over it. Every time you remember something, the memory itself is altered in your mind. We know now that you didn't have a 7600X, but I think it can also be true that you remembered buying one.

If you ordered it online, what does it say on the order history? What does it say your card is in system info?

I think this is the CPU you're looking for : https://www.amd.com/en/products/cpu/amd-ryzen-5-5600x

When you were deciding for this processor, Intel's similarly priced i5s were no match for it, so if you were looking for Intels as well, you likely would have had an eye on the i7 processors of that time (for a minor performance benefit at a heavy price tag). So maybe that is where your 7 is coming from.