So there are quite a few files with the old bucket indeed.
The remap you need should be:
./launcher enter app
rails c
DbHelper.remap("ortus-discourse.s3.dualstack.us-west-2.amazonaws.com", "ortus-discourse-uploads.s3.dualstack.us-west-2.amazonaws.com")
Please take a backup before, as there is no undoing of such operation.