Firebase – Build failed – Could not resolve io.grpc:grpc-core:[1.28.0]. (yes I have upgraded to mavenCentral())

I was able to build and publish my flutter app on October 6th, I returned today on Octuber 30th and I am getting this build error:

• Could not resolve io.grpc:grpc-core:[1.28.0].
• Could not HEAD 'https://jcenter.bintray.com/io/grpc/grpc-core/maven-metadata.xml'.
• Read timed out

It seems there is an issue with cloud_firestore somehow it’s still trying to read from jcenter which I am informed that it’s down and not supporting new repositories, but the issue is that I have not changed a single line nor updated any packages since my last publish and build, what caused this issue?

I remember I had a similar issue a few months ago but everything was fixed after I replaced jcenter with mavenCentral, but this time it’s back again.

Launching libmain.dart on Android SDK built for x86 in debug mode...

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':app:processDebugResources'.
> Could not resolve all task dependencies for configuration ':app:debugRuntimeClasspath'.
   > Could not resolve io.grpc:grpc-core:[1.28.0].
     Required by:
         project :app > project :cloud_firestore > com.google.firebase:firebase-firestore:21.7.1 > io.grpc:grpc-android:1.28.0
         project :app > project :cloud_firestore > com.google.firebase:firebase-firestore:21.7.1 > io.grpc:grpc-okhttp:1.28.0
      > Failed to list versions for io.grpc:grpc-core.
         > Unable to load Maven meta-data from https://jcenter.bintray.com/io/grpc/grpc-core/maven-metadata.xml.
            > Could not HEAD 'https://jcenter.bintray.com/io/grpc/grpc-core/maven-metadata.xml'.
               > Read timed out

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org
BUILD FAILED in 1m 37s
Exception: Gradle task assembleDebug failed with exit code 1
Exited (sigterm)

This is my build.gradle:

buildscript {
    ext.kotlin_version = '1.3.50'
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.6.2'
        classpath 'com.google.gms:google-services:4.3.3'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

allprojects {
    repositories {
        google()
        mavenCentral()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Yes, my app is pretty old, since I have yet to update to null-safety.

Any tips to avoid this issue in the future?

How do I solve this current issue?