I believe that
reference on the link if not a tracking then a affiliate/referral link or code. Just to give you some thoughts, it's not allowed to post referral links but they're allowed to be on the signature space.
4. No referral code (ref link) spam. [1]
It looks a spam since you've included it twice on one post which is your thread starter.
The reference link and the bonus code he provided is matched. This is just my assumption but I believe only casino representatives can give a bonus code like that unless customized bonus code is possible on every affiliate account on that casino.
Also some casino use a tracking link with same manner of affiliate link. They just embedded on the image that’s why it’s not always visible to check.
OP should give proof for his position as representative.