Adobe have announced that from the 1st of May '24 it will not be possible to create a new Service Account JWT and from the 1st of January '25, they will not work at all.
To ensure your Adobe Creative Cloud managed application continues to work, as of Wednesday the 24th of April you will need to reauthorise it using the Oauth2.0 authentication method.
Further details can be found by following the 'Adobe Help' option below.