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in qatar they have tough gambling laws so i doubt they will allow any team to wear a shirt that has a gambling site logo on it, teams know this or at least are supposed to have been informed about this issue, in qatar They even block gambling sites, so you can see that the guys take their persecution of gambling very seriously.
a gambling company could also hire a player as an ambassador without putting a logo on his shirt
but putting his face in the company ads
many ways to do it,
endless possibilities