Bot webhook data `callChainId` no longer persists on transfers

Describe the issue
Recently (around 2022-01-05) the json data we receive on our bot webhook has changed. A call flow such as:

• pstn calls a teams user
• teams user transfers to another user
• both legs would have a matching resourceData.callChainId

Now when transferring the resourceData.callChainId is different and we get resourceData.incomingContext.transferor instead

Expected behavior
We would expect the resourceData.callChainId to persist across a transfer, is this not the purpose of that id?

Graph SDK (please complete the following information):
Not an SDK issue, this the bot webhook configured in Azure.

Additional context
Is this the intended behaviour now? If so is there anywhere we can subscribe to future changes as this is a breaking change.
Also please let me know if there is a more appropriate place to log this issue, it is not clear where this should be reported.

Many thanks!

The issue identifies an Azure bot webhook and the transfer fields resourceData.callChainId and incomingContext.transferor, but names no repository files, tests, or entry points. Start by checking the webhook behavior around transferred calls; this is done only when the intended persistence behavior and an appropriate reporting or subscription path are established.