I think you should use "`TestImplementation libs.androidx.core.ktx`" instead of `"Implementation ...`" In mobile/android/geckoview/build.gradle since GeckoView doens't use Android KTX.
Bug 1956673 Comment 3 Edit History
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I think you should use "`AndroidTestImplementation libs.androidx.core.ktx`" instead of `"Implementation ...`" In mobile/android/geckoview/build.gradle since GeckoView doens't use Android KTX.