Have you looked at the definition in the Regulation?

(xiv) Meaning of trade or business where the principal asset of such trade or business is the reputation or skill of one or more employees or owners. For purposes of section 199A(d)(2) and paragraph (b)(1)(xiii) of this section only, the term any trade or business where the principal asset of such trade or business is the reputation or skill of one or more of its employees or owners means any trade or business that consists of any of the following (or any combination thereof):

(A) A trade or business in which a person receives fees, compensation, or other income for endorsing products or services;

(B) A trade or business in which a person licenses or receives fees, compensation, or other income for the use of an individual's image, likeness, name, signature, voice, trademark, or any other symbols associated with the individual's identity; or

(C) Receiving fees, compensation, or other income for appearing at an event or on radio, television, or another media format.

(D) For purposes of paragraphs (b)(2)(xiv)(A) through (C) of this section, the term fees, compensation, or other income includes the receipt of a partnership interest and the corresponding distributive share of income, deduction, gain, or loss from the partnership, or the receipt of stock of an S corporation and the corresponding income, deduction, gain, or loss from the S corporation stock.

https://www.law.cornell.edu/cfr/text/26/1.199A-5#b_2_xiv