[com.google.android.apps.tachyon] Google Meet fails to register

Affected app
Name: Google Meet (formerly Google Duo)
Package id: com.google.android.apps.tachyon
Affected version: 174.0.471884746.duo.android_20220821.17_p2
(seems to affect all versions as far back as April, when still named Duo)

Describe the bug
Google Meet registration via phone number (required) fails with an error "Something went wrong. Please try again" and log messages showing Received GRPC_REGISTER error and INVALID_ARGUMENT: Request contains an invalid argument. (Log attached further down.)

To Reproduce
Steps to reproduce the behavior:

1. Install Google Meet and open the app.
2. Agree to the terms.
3. Give access to contacts and to make phone calls, or don't. Doesn't matter.
4. Enter a valid phone number.
5. Tap Agree.

Expected behavior
The app registers successfully and is usable.

Screenshots

System
Android Version: 12L
Custom ROM: CalyxOS 3.8.0 (custom build)

microG
microG Core version: 0.2.24.214816-25 (4b20f8b)
microG Self-Check results: All ticked

Additional context
Log: tachyon.log

Log snippet (more in log attached above):

09-12 18:59:10.738  6398  6837 W Grpc    : Received GRPC_REGISTER error (id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx), tachyon-error: 1
09-12 18:59:10.738  6398  6837 W Grpc    : zjm: INVALID_ARGUMENT: Request contains an invalid argument.
09-12 18:59:10.738  6398  6837 W Grpc    : 	at io.grpc.Status.g(Unknown Source:2)
[...]

Start by reproducing Google Meet registration on Android 12L with the reported microG and Meet versions, then inspect the attached tachyon.log around the GRPC_REGISTER INVALID_ARGUMENT error. The issue is done when phone-number registration completes successfully and Google Meet becomes usable.