issue with latest bicep cli Error BCP036: The property "managedIdentity" expected a value of type "object" but the provided value is of type "string"

I am part of a team working on an APIM landing zone. See https://github.com/Azure/apim-landing-zone-accelerator/tree/main/reference-implementations/AppGW-IAPIM-Func/bicep

This bicep for this was working - and then I (and others) got this error
issue with latest bicep cli Error BCP036: The property "managedIdentity" expected a value of type "object" but the provided value is of type "string"

On trying to reproduce this I figured out the only thing that changed was that I upgraded to 1272.
On downgrading back to 1008 (did not try 1124), I noticed the error disappeared. So it seems like ARM generated with 1272 creates an issue

**To Reproduce**
Try the following - clone the repo https://github.com/Azure/apim-landing-zone-accelerator
go into the gateway directory - https://github.com/Azure/apim-landing-zone-accelerator/tree/main/reference-implementations/AppGW-IAPIM-Func/bicep/gateway
do a bicep build of appgw.bicep to generate ARM template
reverse engineer this ARM template back to bicep
Check the errors - Try this with 1272 and 1008

**Additional context**
Add any other context about the problem here.

Clone Azure's apim-landing-zone-accelerator and work in reference-implementations/AppGW-IAPIM-Func/bicep/gateway. Build appgw.bicep with Bicep CLI 1272 and 1008, reverse engineer the generated ARM template back to Bicep, and compare the managedIdentity diagnostics. Done means the version-related type mismatch is reproduced and the round trip no longer reports BCP036.

Written by the indexing model from the issue text.