I and anyone who visits my wishlist page gets the 504 gateway error. I have tested this with a few people and they all report back that they get the 504 gateway error. I am unsure for how long this has been happening for entirely but I know for at least 2 to 3 days this has been the case. It's probably been longer.

Here is the marketplace link:

Thank you to Sine Linden for pointing me here :]