Where is the ambiguity?

To understand §199A-2(b)(2)(ii), you need to read the preamble about comments the IRS had received and why it is structured the way it is.  It is there essentially to provide clarity on how W-2 income would be treated where a qualified trade or business engages professional employer organizations, payroll agents, and similar companies to administer employment formalities and payroll processes on their behalf and where these individuals to whom W-2 wages were paid are common law employees of the qualified trade or business.

If you are referring to an article published by organizations other than the IRS or state DOR, it would help to provide a link.  I looked up that the article from Bessemer Trust and read that differently.  It is clearly referring separate real estate businesses under common control and supported by a management company owned by the parent.  This is a setup contemplated within the regulations and not related to your scenario where the property management company is an unrelated third party service provider.

W-2 wages paid by third party property management companies to their employees are not relevant to rental enterprises although hours they incur in rendering rental services with respect to rental enterprises electing for safe harbor under Notice 2019-07 are counted towards the 250-hour requirement.

You can't argue that property owners have sufficient management and control over employees of these property management companies.  These owners sign an agreement with the property management company, which stipulates the terms and conditions of the engagement, and none of which would include direct supervision, control over the means of delivering services, power to hire and fire, pay decisions, among other things.  I doubt property owners want to be a common law employer of these individuals because being one comes with various liabilities.