Francis Ngannou is the former "Lineal Combat Sports Heavyweight Champion 🏆" of the world but NOT the former UFC Lineal Combat Sports Heavyweight Champion of the world.

To wit:

ARTlCLE XVI  PROHIBITION  ON USE OF INTELLECTUAL PROPERTY RIGHTS

16.1     Unless Fighter receives prior written approval from ZUFFA, Fighter shall not utilize any of ZUFFA's intellectual property rights, including, but not limited to, the names and marks "Ultimate Fighting Championship," "UFC," the "Octagon," "Ultimate Fighting," " Ultimate Fighter," and any logos, pictures or other representations of ZUFFA's intellectual property. Without limiting the scope of this prohibition, Fighter expressly agrees that he may not refer to himself as a "UFC Champion"; "former UFC Champion"; "UFC Star"; "UFC Superstar"; "UFC Fighter" or utilize any of ZUFFA's intellectual property in describing or referring to himself, without the express written consent of ZUFFA. Further, Fighter expressly agrees not to use a UFC Championship belt without the prior, written approval of ZUFFA, and further agrees that any such belt he obtains is on loan and will at all times remain the property of ZUFFA. Upon ZUFFA's written request, the belt must be returned within forty-eight (48) hours to ZUFFA at Fighter's expense. Additionally, Fighter expressly acknowledges and agrees that ZUFFA is not a sanctioning organization and Fighter does not possess and cannot assert any property right or similar legal interest in the UFC Title or in being a UFC Champion.

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End Notes:
I'm no legal expert at all but I would include the pronoun "she" for their female athletes.

Surprisingly, Randy Couture and Frank Shamrock mentions the UFC in their Twitter bios. Tito Ortiz, Cris Cyborg and the aforementioned Francis Ngannou are legally safe according Article XVI, Section 16.1.

Interesting, Georges St. Pierre, Demetrious "Mighty Mouse" Johnson, and Sean Strickland have no mentions of the UFC in their Twitter bios.