Seems I am too dumb :)
I have my xapk (BB.xapk), which I converted with:
java -jar APKEditor-1.4.5.jar m -i "BB.xapk"
Decompiled it with:
apktool d BB_merged.apk -o BBSrc
Changed the AndroidManifest (the game is using Applovin, so it was modified to 'com.safedk.android.SafeDKApplication')
Afterwards, I recompiled it:
apktool b BBSrc -o BB.apk
Now I needed to grab the original APK for the sig, so I extracted BB.xapk, which got me the config.arm64_v8a.apk and the com.bubble.blaster.apk
I copied my BB.apk and the original com.bubble.blaster.apk to my Android phone, updated the BB.apk CRC32 with the one from com.bubble.blaster.apk, and installed the newly created Edit_Sign apk.
Result:
App instantly opened that stupid protect shit
