I’m trying to login here --> https://canvas.fediverse.events/ but can’t seem to.

Maybe this helps?

curl 'https://auth.fediverse.events/api/v1/login/step/username' \  
  -H 'Accept: */*' \  
  -H 'Accept-Language: en-US,en;q=0.7' \  
  -H 'Connection: keep-alive' \  
  -H 'Content-Type: application/json' \  
  -b 'connect.sid=s%3AyUrOl_jKXQ...removed.for.reasons...2wm7rkbzw5wdkvg2%2Bdzw' \  
  -H 'Origin: https://auth.fediverse.events/' \  
  -H 'Referer: https://auth.fediverse.events/login?return=%2Finteraction%2F5_Yx..removed..oAld' \  
  -H 'Sec-Fetch-Dest: empty' \  
  -H 'Sec-Fetch-Mode: cors' \  
  -H 'Sec-Fetch-Site: same-origin' \  
  -H 'Sec-GPC: 1' \  
  -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36' \  
  -H 'sec-ch-ua: "Not)A;Brand";v="8", "Chromium";v="138", "Brave";v="138"' \  
  -H 'sec-ch-ua-mobile: ?0' \  
  -H 'sec-ch-ua-platform: "Linux"' \  
  --data-raw '{"username":"Ek-Hou-Van-Braai","instance":"piefed.social"}'