APK signed with incorrect Key

I have created an app using flutter and I signed it by following the official documentation here. I build it successfully but when I checked the APK using this website

1. APK signed with the correct key
2. Key storage password is correct.
3. The password for the signing key is correct.

are not checked

Here is the screenshot

The android/key.properties file

storePassword=pdP1CV05UyUWGKrXtTX00m
keyPassword=pdP1CV05UyUWGKrXtTX00m
keyAlias=key
storeFile=./key.jks

The app/build.gradle file

def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
if (keystorePropertiesFile.exists()) {
  keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
}
 signingConfigs {
   release {
       keyAlias keystoreProperties['keyAlias']
       keyPassword keystoreProperties['keyPassword']
       storeFile keystoreProperties['storeFile'] ? 
 file(keystoreProperties['storeFile']) : null
       storePassword keystoreProperties['storePassword']
   }
 }
 buildTypes {
   release {
       signingConfig signingConfigs.release
   }

}

What did I miss? I am gonna lose myself.