In "TestRegistration/parallel/POST_{}_returns_a_set_of_flows" the test strictly required application/json. It's common for many servers to return also a charset in the content type, which is valid according to HTTP. However, complement considers this as a failure which I discovered while testing https://github.com/MTRNord/persephone :)
https://github.com/matrix-org/complement/blob/ad263aa5d0dfbd823d99e486642d71f402a07ffa/tests/csapi/apidoc_register_test.go#L50-L52
In "TestRegistration/parallel/POST_{}_returns_a_set_of_flows" the test strictly required application/json. It's common for many servers to return also a charset in the content type, which is valid according to HTTP. However, complement considers this as a failure which I discovered while testing https://github.com/MTRNord/persephone :)