@jimbateson With basically everything involved deprecated on Netlify’s side of things, you’re almost certainly going to be better off seeking assistance and recommendations from Decap’s community.
There’s a related GitHub discussion here:
https://github.com/decaporg/decap-cms/discussions/7419
In which a user promotes their own solution:
https://decapbridge.com/
The Decap documentation also lists these other oauth clients:
https://decapcms.org/docs/external-oauth-clients/
If you would like to facilitate your own OAuth authentication rather than use Netlify’s service or a client side flow like implicit or PKCE, you can use one of the community-maintained projects below.
…
Check each project’s documentation for instructions on installation and usage.