@baris Using the below site, reminding me of just how powerful Chrome Developers tools are, I was able to Copy As Curl the specific PUT command.

Curl Convert

Then using the same command and just changing the CID, I confirmed the same command works for all of them.

This is what ended up working, it includes all the recorded headers, of which some will be removed as not necessary:

curl 'http://pubdump.unfufadoo.net:4567/api/v3/categories/80' \
  -X 'PUT' \
  -H 'Connection: keep-alive' \
  -H 'Accept: */*' \
  -H 'DNT: 1' \
  -H 'x-csrf-token: H5FMJEaY-CthHWM_2Unzf7DtoPeryGq_JejE' \
  -H 'X-Requested-With: XMLHttpRequest' \
  -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.81 Safari/537.36' \
  -H 'Content-Type: application/json; charset=UTF-8' \
  -H 'Origin: http://pubdump.unfufadoo.net:4567' \
  -H 'Referer: http://pubdump.unfufadoo.net:4567/admin/manage/categories/80' \
  -H 'Accept-Language: en-US,en;q=0.9,zh;q=0.8,zh-CN;q=0.7,zh-TW;q=0.6,ja;q=0.5,ko;q=0.4,th;q=0.3' \
  -H 'Cookie: _csrf=27ygKMdG0c0EyiVsJKAkKpId; express.sid=s%3AdODaXfUpLz7NTFsijWLq0d2rPUhH1Ki4.qkyxWOaxlBy%2BLDRpTYbhWS9QkD9IJE%2FRTN1vIhp7yV4' \
  -H 'sec-gpc: 1' \
  --data '{"backgroundImage":"/assets/uploads/category/category-84.jpg"}' \
  --compressed \
  --insecure

Then using the cURL convert site, was able to save as javascript and modify to our needs so that we could loop through all categories.

Jeff