Android SDK logs error 422 when sending a support request

Hey Zendesk Community,

My app, Udemy, mysteriously stopped allowing users to send Zendesk support tickets, with no known code change in the app's Zendesk facing code. Six months ago, I faced the same exact issue  (https://support.zendesk.com/hc/requests/6700021 - previously deleted by Zendesk for some reason) and discovered one of the non-null custom fields was being populated with a null. Now, it's the same issue but a different cause. 

Here are the logs from enabling logging (Logger.setLoggable(true)). You can see a 422 error with no message about what specifically is broken.

D/RequestActivity: Waiting for attachments to be uploaded. Message Id: 5871469887153719211
D/RequestActivity: Notify if finished. Listener: zendesk.support.request.ActionCreateComment$1@25a9b62, isUploadFinished: true
D/RequestActivity: Attachments resolved and uploaded. Message Id: 5871469887153719211
D/RequestActivity: Creating a new request. Message Id 5871469887153719211
D/ZendeskSettingsProvider: Successfully retrieved Settings
D/SupportSdkMetadata: Using getTotalMemoryApi() to determine memory
D/SupportSdkMetadata: Using getTotalMemoryApi() to determine memory
D/ZendeskRequestProvider: Adding tags to feedback...
D/ZendeskIdentityStorage: Loading Jwt identity
I/okhttp.OkHttpClient: --> POST https://ufb.zendesk.com/api/mobile/requests.json?include=last_comment (738-byte body)
D/SettingsInterceptor: Proceeding with chain.
D/ZendeskIdentityStorage: Loading Jwt identity
D/ZendeskAccessIntercepto: Access token present, no need to intercept.
D/GsonSerializer: Unable to deserialize the provided object into PushRegistrationRequest
I/okhttp.OkHttpClient: <-- 422 https://ufb.zendesk.com/api/mobile/requests.json?include=last_comment (724ms, 161-byte body)

Relevant config
1. I can send you the account's email sending the request if necessary
2. Version: com.zendesk:support:5.0.2