A pair of First Order stormtroopers patrolling Kijimi City in 35 ABY reported on the T-18. One of them asked if the T-18s were online yet, to which another replied that they were online and scouting the perimeter.
The T-18 mention was added by voice actor Sam Witwer as a reference to a conversation in between two stormtroopers who are discussing the BT-16 while Obi-Wan Kenobi disables the tractor beam. Witwer also added similar lines in the Rogue One: A Star Wars Story and Solo: A Star Wars Story, which mention the T-15, and and which mention the T-17. Similar reference to the T-16 was added in "Part III" of the series Obi-Wan Kenobi. The mention depended on the era.
The T-18 mention was added by voice actor Sam Witwer as a reference to a conversation in between two stormtroopers who are discussing the BT-16 while Obi-Wan Kenobi disables the tractor beam. Witwer also added similar lines in the Rogue One: A Star Wars Story and Solo: A Star Wars Story, which mention the T-15, and and which mention the T-17. Similar reference to the T-16 was added in "Part III" of the series Obi-Wan Kenobi. The mention depended on the era.