Source: Ilhoon IG | BTOBSTORYY
The maknaes really did enlist early. Sungjae & Ilhoon probably planned this so they'll be complete on their 10th year anniv March 2022. Serve well Ilhonieee!
Edit: Updated the title coz after a few hours, it was confimed that he's enlisting today. Also, his discharge date is February 2022 since he'll be a public service worker.