>They'll just say the tracking is part of the business model and therefore needed to provide the service.
This is unacceptable under the GDPR. You must allow users to opt out. If this affects your business model than the legal option is to remove the free plan and charge a fee for the service.
This is unacceptable under the GDPR. You must allow users to opt out. If this affects your business model than the legal option is to remove the free plan and charge a fee for the service.