Pleroma users (admin & ordinary) cannot change password via pleroma-fe (API 400/Bad Request)

Environment

1. pleroma 2.4.0-516-gdc63aaf8 (OTP), pulled today via curl "https://git.pleroma.social/api/v4/projects/2/jobs/artifacts/stable/download?job=amd64" -o pleroma_amd64.zip
2. OS: Ubuntu 20.04.2 LTS (64-bit)
3. Browser: firefox 90.0.2 (64-bit) for Ubuntu canonical 1.0

Issue

1. Install looks fine. Access with browser looks fine.
2. Admin new user via CLI and login via browser, no problem.
3. New user (non-admin) creation via pleroma-fe, no problem.
4. Neither admin nor ordinary user can use pleroma-fe to change password.
5. The issue is the same whether using AdminFE or not.

What I see

1. POST is made to /api/pleroma/change_password with response 400 / Bad Request.
2. UI indicates each of password, new_password, and new_password_confirmation are missing.
3. Request does contain form-data; name="password" "new_password" and "new_password_confirmation" data is present as entered in the form.
4. Response contains an error object indicating the missing data, as well as a list of three items, one for each field, indicating pointers /password, /new_password, and /new_password_confirmation have titles Invalid value.

What I expect

1. Successful password change and confirmation.

I searched "password" on both pleroma & pleroma-fe gitlab for "password" without any luck. I posted the issue to #pleroma @ libera.chat today without response. Raising the issue here as a result.

I've successfully installed have been using a single-user pleroma instance for several months, so I haven't had cause to detect when this issue may have appeared. I spotted this running some tests for a new potentially multi-user install.

How can I help?