Invalid SplitApkBundle. The bundle targets unknown languages: [gr]. google play console

I had the same issue.
Invalid SplitApkBundle. The bundle targets unknown languages:[cb]

I solved by setting DSL to stop aapt package building the wrong language targets.

My app supports English and Chinese, therefore resConfigs only needs en and zh.

defaultConfig {
    ...
    resConfigs "en", "zh-rTW", "zh-rCN"
}

Apply this to Android{}

bundle {
    density {
        // Different APKs are generated for devices with different screen densities; true by default.
        enableSplit true
    }
    abi {
        // Different APKs are generated for devices with different CPU architectures; true by default.
        enableSplit true
    }
    language {
        // This is disabled so that the App Bundle does NOT split the APK for each language.
        // We're gonna use the same APK for all languages.
        enableSplit false
    }
}

in my case i was because i was using facebook account kit see wells answer it helped me out , i am in lining it here for future references

bundle {
    density {
        // Different APKs are generated for devices with different screen densities; true by default.
        enableSplit true
    }
    abi {
        // Different APKs are generated for devices with different CPU architectures; true by default.
        enableSplit true
    }
    language {
        // This is disabled so that the App Bundle does NOT split the APK for each language.
        // We're gonna use the same APK for all languages.
        enableSplit false
    }
}