Ersan Ilyasova was supposedly measured at 6-8 without shoes by the NBA's Milwaukee Bucks in 2019, for the NBA's new rule that every team had to provide updated height listings to the league, and also that the teams had to provide the league with what the heights of their players was without shoes on. The Bucks listed Ilyasova as having measured at 6-8 without shoes on.
In this picture, Alperen Sengun is clearly taller than Ilyasova. And Ilyasova also appears to be a bit closer to the camera, which would make him seem to be a bit taller by comparison, due to the camera angle.
Sengun is also standing next to Cedi Osman, who the Cavs supposedly measured at 6-7 barefoot. Sengun is noticeably taller.
The NBA's decades long "in shoes" height listing criteria (in shoes and rounded up), which is what people are thinking of when they come up with these so and so player is "undersized" views, Ilyasova would be listed at 6-9 or 6-10 (he was in fact previously listed at 6-10 by the NBA), and Osman would be listed at 6-8 or 6-9 (he was actually previously listed at 6-8 by the NBA).
In other words, the height that some people are claiming for Sengun, "6-8 or 6-9 in shoes", is actually the height that Osman is, and Sengun is definitely taller, as can be seen in that picture.
All of the speculation over these recent months that Sengun is, "only 6-8 or 6-9 in shoes", can officially end now.
