If you haven’t tried it already, you may gain more info following the docs’ troubleshooting/debugging advice:
SSH into your server and manually run the command where Ansible failed.
Example: if a Git clone task failed during deploys, then SSH into the server as the web user (which is what deploys use) and run the manual command such as git clone . This will give you a much better clue as to what’s going wrong.
Running git clone on the server may reveal the problem, or may simply prompt you to accept the host key, after which deploys may work fine.
Ultimately you’ll want to update Trellis. For keeping Trellis updated, some keep their Trellis separate from Bedrock and Sage (basic idea). Others maintain a project combining Trellis, Bedrock, and Sage, using subtrees or cherry-picking commits (recommended).
I think a lot of people just update Trellis manually, grabbing the latest files from upstream master then 1) pasting in upstream files that they themselves haven’t customized in their local projct, then 2) identifying and incorporating updates in files they have modified (like group_vars files), then 3) committing the changes.