According to #154915, Apple will start requiring privacy manifests for macOS on November 12, 2024:

ITMS-91061: Missing privacy manifest - Your app includes “Contents/Frameworks/FlutterMacOS.framework/Versions/A/FlutterMacOS”, which includes Flutter, an SDK that was identified in the documentation as a privacy-impacting third-party SDK. Starting November 12, 2024, if a new app includes a privacy-impacting SDK, or an app update adds a new privacy-impacting SDK, the SDK must include a privacy manifest file. Please contact the provider of the SDK that includes this file to get an updated SDK version with a privacy manifest. For more details about this policy, including a list of SDKs that are required to include signatures and manifests, visit: https://developer.apple.com/support/third-party-SDK-requirements.

The macOS plugin template flutter create --template plugin should include an empty privacy manifest similar to #140013. NSPrivacyTracking* and NSPrivacyCollectedDataTypes keys are required, but the values can be blank. macOS explicitly does not need the NSPrivacyAccessedAPITypes (see more info in #143381)

See the iOS PR #148485 for what work needs to be done for this.