The location to the flutter SDK may be found in the setting.json file.
1) tap ctrl+shift+p
2) tap ctrl+shift+p
3) open setting.json
in that file you maybe found
"dart.flutterSdkPath": "C:\\tools\\flutter_sdk_3.0.4\\flutter\\bin",
"dart.sdkPath": "C:\\tools\\flutter_sdk_3.0.4\\flutter\\bin\\dart",