check_event_allowed callback from the module API cause a TypeError

[c-cal]

Description

ThirdPartyEventRulesModuleApiCallbacks.check_event_allowed() freezes incoming events for safety purpose, but the Rust implementation of PushRuleEvaluator doesn't seem to handle immutabledict.

Steps to reproduce

1. extend the server config with

   default_power_level_content_override:
     public_chat:
       notifications:
         room: 0

2. register a module which register a check_event_allowed callback. The callback could do nothing, eg: return (True, None)
3. try to create a public room to see the bug

Homeserver

a local homeserver

Synapse Version

v1.122.0

Installation Method

Docker (matrixdotorg/synapse)

Database

PostgreSQL 15

Workers

Single process

Platform

Ubuntu 24.04

Configuration

No response

Relevant log output

File "/usr/local/lib/python3.12/site-packages/synapse/push/bulk_push_rule_evaluator.py", line 429, in _action_for_event_by_user
     evaluator = PushRuleEvaluator(
                 ^^^^^^^^^^^^^^^^^^
 TypeError: argument 'notification_power_levels': 'immutabledict' object cannot be converted to 'PyDict'

Anything else that would be useful to know?

No response