When changing a proto file like adding an argument to a message, it does not seem to take effect unless you make a new request/duplicate the current one. I've refreshed the schema, removed/readded the proto file and it still seems to say "unrecognized field name '...' at line 7 column 12".
Restarting Yaak appears to solve the issue.
Version 2024.6.6 (20240618.001507)