Hi. I tried with 'client_secret_post', but only an error appears ('invalid_client').
(No changes have been made to the source file.)

but, It works if I try after changing to 'client_secret_basic'. (client_metadata)

work request format:

Can you make it work in the 'client_secret_post' way?
Maybe I'm trying to do something wrong, but I can't solve it even if I change various ways.