Docker Function automated deployment (image pull) inexplicably switches to different CR container

Question

We've had a bit of an odd incident with one of our Azure Functions, and I really can't explain what happened.

We're using a number of Docker-based Azure Functions. All of these run a small process every fifteen minutes.
They run Docker images that are pushed to an Azure Container registry via a standard Azure Devops Build + Release pipeline setup.

This has worked without incident until last Friday, when both instances of one of the Functions stopped working.
The logs showed that from that point, the Function was trying to do a 'latest' image-pull from a completely different container in the CR (that it thas no access to).
No changes have been made to the deployment settings, and the last new ci/cd deploy was done almost a month ago. It had been untouched and working fine since then.

The one thing that jumps out at me is that if I go to 'Container Settings (classic)' and manually switch from 'Azure Pipelines' to 'Container Registry', the CR and Image that are shown initially are the ones that it was trying to pull from. It's almost as if it's switched Source settings without showing it in the GUI.

I initially tried running a new Build + Release pipeline, to see if that would trigger a new, correct image pull. It did not.
I then switched to Source 'Container Registry' in the Container Settings Classic, pointed those settings at the correct CR and Image + version, saved these settings and then switched the settings back to Source 'Azure Pipelines' and saved again.
It's now once again showing 'Azure Pipelines' as the deployment Source but the Function is working again and pulling the Image from the CR, with the version I had temporarily selected in the previous step.

All other Functions have not had this issue. The one notable difference is that the others have seen new frequent deployments, and this one has been running as-is for almost a month untouched before breaking down.

I have no clear idea what happened, nor why it happened.
Anyone recongnize this behavior or can offer suggestions on what to check for?