When I do a curl request to the feddit.online API endpoint I can log in fine. If I use an invalid password I get the expected error message.

rimu@rimu-mate2 ~ $ curl --request POST \
  --url https://feddit.online/api/alpha/user/login \
  --header 'Content-Type: application/json' \
  --data '{
  "username": "rimu",
  "password": "valid password"
}'
{"jwt":"some gibberish"}
rimu@rimu-mate2 ~ $ curl --request POST   --url https://feddit.online/api/alpha/user/login   --header 'Content-Type: application/json'   --data '{
  "username": "rimu",
  "password": "invalid password"
}'
{"code":400,"message":"incorrect_login","status":"Bad Request"}