Additional context

• Videos fail to play the requested video when POSTing to /videoplayback. This endpoint returns 403. The request itself did not yield anything useful when skimmed over. The payload is protobuf encoded and some data is likely hashed. No helpful information was inferred from the URL queries or request headers. I also imagine this issue's origin can come from a completely unrelated request (for example, for token exchange and use in /videoplayback).

• This issue is ONLY reproducible on certain accounts in certain regions due to A/B testing, but expected to roll out globally. I have been able to reproduce this issue with multiple people's devices and ROMs (by using the same affected account), but many people reported this issue on their own accounts as well. On r/revancedapp some references can be found here: #1, #2.

  Note: The YouTube app including MicroG was altered so they can work on stock ROMs, but the issue does not originate from the changes. because we were able reproduce this on the regular YouTube app and on the regular version of MicroG on different custom ROMs.

  An additional confirmation this issue is unrelated to the modifications on YouTube or MicroG is that when the modified app is altered back to use Google Services instead of MicroG, this issue does not occur. This was achieved by mounting the app with mount and root permissions on top of the regular unmodified app, allowing it to bypass the measurements from GMS to prevent unauthorized apps from using GMS such as the modified YouTube app. To sum up, this issue occurs on unmodified YouTube and upstream MicroG.

  To solve this issue, I am willing to contribute with accounts from my side on which this issue can be fully reproduced.

• This issue can be reproduced as well on older versions of YouTube. It is unlikely the issue originates from the app and in combination with the other additional context it is assumed, the issue is related to MicroG.

• Related exception stack traces from YouTube v17.49.37 when the issue occurs:

  •  OException when handling a request
     cn: Response code: 403
         at bdf.b(PG:37)
         at yte.b(PG:20)
         at zlr.b(PG:1)
         at yso.b(PG:2)
         at mfg.b(PG:16)
         at zlr.b(PG:1)
         at yss.b(PG:22)
         at zlr.b(PG:1)
         at yrg.b(PG:54)
         at bcv.b(PG:48)
         at bcr.b(PG:2)
         at abxf.b(PG:2)
         at bcx.b(PG:1)
         at mda.i(PG:19)
         at mda.b(PG:17)
         at bbw.a(PG:1)
         at bbw.read(PG:5)
         at bbw.read(PG:3)
         at afyw.a(PG:3)
         at abwx.writeTo(PG:3)
         at org.apache.http.impl.entity.EntitySerializer.serialize(EntitySerializer.java:102)
         at org.apache.http.impl.AbstractHttpServerConnection.sendResponseEntity(AbstractHttpServerConnection.java:187)
         at org.apache.http.protocol.HttpService.handleRequest(HttpService.java:214)
         at abxa.run(PG:5)
         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1137)
         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:637)
         at syj.run(PG:22)
         at java.lang.Thread.run(Thread.java:1012)
    

  •  Given up trying to get FCM Registration Id:
     java.io.IOException: SERVICE_NOT_AVAILABLE
          at ndo.a(PG:11)
          at nne.run(PG:54)
          at rt.execute(PG:6)
          at nso.a(PG:8)
          at abmg.i(PG:5)
          at nsz.s(PG:3)
          at nne.run(PG:59)
          at rt.execute(PG:12)
          at nso.a(PG:8)
          at abmg.i(PG:5)
          at nsz.s(PG:3)
          at ntm.b(PG:1)
          at mut.d(PG:1)
          at muv.a(PG:2)
          at bnp.handleMessage(PG:43)
          at android.os.Handler.dispatchMessage(Handler.java:102)
          at android.os.Looper.loopOnce(Looper.java:201)
          at android.os.Looper.loop(Looper.java:288)
          at android.app.ActivityThread.main(ActivityThread.java:7872)
          at java.lang.reflect.Method.invoke(Native Method)
          at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)