The issue is that you can run the test only once on the emulator, after that CLEAR STORAGE of the tst_qaudiosource on App info or it must be uninstalled if you want to run it again.

After first run:
...
 QTestLib: PASS : tst_QAudioSource::cleanupTestCase()
I QTestLib: Totals: 41 passed, 0 failed, 0 skipped, 0 blacklisted, 27105ms
I QTestLib: ********* Finished testing of tst_QAudioSource *********
W libtst_qaudiosource_x86.so: exit app 0

After second run and etc.:
...
I QTestLib: ********* Start testing of tst_QAudioSource *********
I QTestLib: Config: Using QtTest library 6.4.0, Qt 6.4.0 (i386-little_endian-ilp32 shared (dynamic) debug build; by Clang 9.0.9 (https://android.googlesource.com/toolchain/llvm-project a2a1e703c0edb03ba29944e529ccbf457742737b)), android 9.0
W System.err: java.lang.NoSuchMethodError: no static method "Lorg/qtproject/qt/android/multimedia/QtAudioDeviceManager;.registerAudioHeadsetStateReceiver(Landroid/content/Context;)Z"
W System.err: at org.qtproject.qt.android.QtNative.startQtApplication(Native Method)
W System.err: at org.qtproject.qt.android.QtNative$7.run(QtNative.java:658)
W System.err: at org.qtproject.qt.android.QtThread$1.run(QtThread.java:61)
W System.err: at java.lang.Thread.run(Thread.java:764)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xf16cea00) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xe9a13600) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69fd000) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69fd600) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69fdc00) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69fe200) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69fe800) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69fee00) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69ff400) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd69ffa00) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd39fa000) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd39fa600) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
E IAudioFlinger: createRecord returned error -22
E AudioRecord: AudioFlinger could not create record track, status: -22
E libOpenSLES: android_audioRecorder_realize(0xd39fac00) error creating AudioRecord object; status -22
W libOpenSLES: Leaving Object::Realize (SL_RESULT_CONTENT_UNSUPPORTED)
I QTestLib: FAIL! : tst_QAudioSource::initTestCase() 'testFormats.size()' returned FALSE. ()
I QTestLib: Loc: [/home/pekka/dev_qt6_second/qt6/qtmultimedia/tests/auto/integration/qaudiosource/tst_qaudiosource.cpp(175)]
I QTestLib: PASS : tst_QAudioSource::cleanupTestCase()
I QTestLib: Totals: 1 passed, 1 failed, 0 skipped, 0 blacklisted, 322ms
I QTestLib: ********* Finished testing of tst_QAudioSource *********
W libtst_qaudiosource_x86.so: exit app 0

After uninstall and first run:
...
I QTestLib: PASS : tst_QAudioSource::cleanupTestCase()
I QTestLib: Totals: 41 passed, 0 failed, 0 skipped, 0 blacklisted, 35024ms
I QTestLib: ********* Finished testing of tst_QAudioSource *********
W libtst_qaudiosource_x86.so: exit app 0