literally a lot of people called it...
first it started off with him going to the Burberry event this Summer, then him posting 5-6 Burberry sponsored ads on his Instagram page
people also pointed out how he started wearing Burberry more than usual over the past couple of months, the most recent was him at the airport 3 days ago
and just 2 days ago i believe, the official Burberry account literally liked and commented on his recent ad post for them, which a lot of people was saying they BARELY ever like sponsored posts by people, let alone comment
NOW fast forward TODAY some hours ago, it was announced he is going to be on the FRONT COVER of GQ Korea magazine
They called it "GQ Korea November issue exclusive cover with Burberry", which means Burberry partnered with Yeonjun for the shoot and wanted HIM to represent it.
(btw he's also the brand ambassador for EXO Baekhyuns clothing line Prive Alliance, and they said they want Yeonjun to sign with them again after their current contract is over cuz he brought in alot of sales and is a great model)
IT'S SO CLEAR THAT BURBERRY IS GOING TO MAKE Yeonjun THEIR BRAND AMBASSADOR.
[THEY DID THIS SAME EXACT INSTANCE WITH CHA EUNWOO, THEY LIKED HIS AD POST IN JUNE (i think this was last year 2021), AND THEN IN JULY (A MONTH LATER) THEY ANNOUNCED HIM AS THE BRAND AMBASSADOR.]
YEONJUN as the new brand ambassador of Burberry soon ya'll..this is just the beginning for his fashion/modeling career! 
