Even with same host there can be differences in the config of the account - at this point the best option is to contact the host and ask about this situation.
Also, you havent c/ped the redirect uri values yet.
Hi
Thank you for your
patience. This is what the hosts say:
Hi Lisa,
I’ve had a look, and as you are using your reseller
account it’s the same server - it’s also running the same php
version 7.3 so the sites are treated identically by the server.
Do you have any different plugins (such as word-fence) which may
have stricter rules than on the older site?
I can’t see any other differences (indeed I can’t
think of any other differences there could be)."
What do I need to do with the redirect urls?
You can just copy each redirect uri, and send them to me in a DM via the forum.