Cannot Connect WordPress

I see this issue mentioned on other closed threads, as old as two years, where the first step of connecting to WordPress fails with:

Invalid request, please go back and try again.
Error Code: invalid_client
Error Message: Unknown client_id.

We do not nor do we want to ever use JetPack. It is notoriously buggy and nearly always a cause of conflict with something. Even hosts like Elementor Cloud Hosting refuse to allow it to be installed. While it is said that JetPack is not required to use the plugin, how is it that this error might be remedied?

I have disabled WordFence and logged into WordPress.com, neither of which helped, both were suggested in other support feeds.