The initial suspicion is due to indexing issues

You can use the PowerShell cd to the root of your Flutter project, run the following command: flutter clean, and then reopen Android studio. If that doesn't work, follow these steps:

# stop all Gradle service
./gradlew --stop

# kill all java process
Stop-Process -Name "java" -Force -ErrorAction SilentlyContinue

#clean all flutter lock files

rm f:\flutter(replace with your path)\bin\cache\lockfile -ErrorActionSilentlyContinue

flutter clean