Section 199-A was highly influenced by real estate lobbyist. Special preference was given to owners of REITs as were owners of qualified property in the form of real estate.
Note the wording on page 21 of the TCJA BLUE BOOK:
'For taxable years beginning after December 31, 2017, and before January 1, 2026, an individual taxpayer generally may deduct 20 percent of qualified business income with respect to a partnership, S corporation, or sole proprietorship, as well as 20 percent of aggregate qualified REIT dividends, qualified cooperative dividends,104 and qualified publicly traded partnership income."
It does not list REIT dividends as QBI along with that from a partnership, S corporation, or sole proprietorship but instead states "as well as 20 percent of aggregate qualified REIT dividends...". Page 29 of the blue book specifically states that a 199-A deduction is allowed for "qualified" REIT dividends etc. There is similar wording in prop reg 1-199A 3(a).
The law expands the deduction beyond QBI to include "qualified" dividends from REITs, therefore an investment in a REIT does not have to rise the to level of a trade or business under section 162 as does a real estate rental.
As I read it, a dividend from a REIT qualifies under section 199-A as long as it would not otherwise receive capital gains tax preference.