"User" Object no longer updates "updated_at" when clearing a field

Up until February 2nd, when on an existing User object a field (e.g. the "Alias" field) was cleared out, the "updated_at" value got changed (indicating that a change happened).

Starting from February 3rd, this is no longer true for clearing a value, the "updated_at" remains the same. When changing or setting a field value, "updated_at" still gets updated.

I didn't see anything in the changelog that would explain this behaviour, so maybe a regression?

Here is a shortened request/response that shows this behaviour:

### Retrieve existing Zendesk User

apache.http.headers - http-outgoing-0 >> GET /api/v2/users/423767055932.json HTTP/1.1
apache.http.headers - http-outgoing-0 << HTTP/1.1 200 OK
apache.http.headers - http-outgoing-0 << Date: Thu, 10 Feb 2022 13:38:47 GMT

{
	"user":{
		"id":423767055932,
		"url":"https://xyz.zendesk.com/api/v2/users/423767055932.json",
		"name":"test user",
		"created_at":"2022-02-10T13:38:45Z",
		"updated_at":"2022-02-10T13:38:46Z",
		"alias":"test alias",
		.....
	}
}


### Update that user's Alias field to 'null'

Payload:  {"user":{"alias":null}}

apache.http.headers - http-outgoing-0 >> PUT /api/v2/users/423767055932.json HTTP/1.1
apache.http.headers - http-outgoing-0 << HTTP/1.1 200 OK
apache.http.headers - http-outgoing-0 << Date: Thu, 10 Feb 2022 13:38:53 GMT

### Retrieve the Zendesk User again

apache.http.headers - http-outgoing-0 >> GET /api/v2/users/423767055932.json HTTP/1.1
apache.http.headers - http-outgoing-0 << HTTP/1.1 200 OK
apache.http.headers - http-outgoing-0 << Date: Thu, 10 Feb 2022 13:38:58 GMT

{
	"user":{
		"id":423767055932,
		"url":"https://xyz.zendesk.com/api/v2/users/423767055932.json",
		"name":"test user",
		"created_at":"2022-02-10T13:38:45Z",
		"updated_at":"2022-02-10T13:38:46Z",
		"alias":"",
		....
	}
}