I'll be watching JoJo on 9anime, cast the webpage it to my Chromecast and fullscreen it (casting just the player doesn't work), then within 30 minutes the screen will freeze for a few seconds then the system will reboot. It only happens when casting the webpage. It doesn't seem to be related to my GPU undervolt - changed it to 'Power Save' in the Radeon settings and it still crashed - doesn't seem to be driver related - happens on 19.9.3 and 19.11.1 - my system is otherwise stable.
I don't know if an XML of the event would be helpful, but I'm not sure what tool to use otherwise as it isn't a BSOD.

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
[B]- <System>
<Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331c3b3a-2005-44c2-ac5e-77220c37d6b4}" />

<EventID>41</EventID>

<Version>6</Version>

<Level>1</Level>

<Task>63</Task>

<Opcode>0</Opcode>

<Keywords>0x8000400000000002</Keywords>

<TimeCreated SystemTime="2019-11-26T16:58:32.330087500Z" />

<EventRecordID>84048</EventRecordID>

<Correlation />

<Execution ProcessID="4" ThreadID="8" />

<Channel>System</Channel>

<Computer>Greyscale</Computer>

<Security UserID="S-1-5-18" />

</System>


- <EventData>
<Data Name="BugcheckCode">0</Data>

<Data Name="BugcheckParameter1">0x0</Data>

<Data Name="BugcheckParameter2">0x0</Data>

<Data Name="BugcheckParameter3">0x0</Data>

<Data Name="BugcheckParameter4">0x0</Data>

<Data Name="SleepInProgress">0</Data>

<Data Name="PowerButtonTimestamp">0</Data>

<Data Name="BootAppStatus">0</Data>

<Data Name="Checkpoint">0</Data>

<Data Name="ConnectedStandbyInProgress">false</Data>

<Data Name="SystemSleepTransitionsToOn">0</Data>

<Data Name="CsEntryScenarioInstanceId">0</Data>

<Data Name="BugcheckInfoFromEFI">false</Data>

<Data Name="CheckpointStatus">0</Data>

</EventData>


</Event>