I have to wonder what the adventurer's guild was thinking by revealing the name and appearance of the adventurer who fulfilled this important request to the physician's guild.
The whole point of the adventurer's guild is that they handle interaction with the clients and with the adventurers, so they should be checking the quality of the adventurer's work and then providing the requested material to the client and at no point should the client ever have to interact with an adventurer so they shouldn't be disclosing their names. I mean, when Yajin took the request, the receptionist only told him that the apothecary would prepare for it, not the exact name of those who had commissioned the request. But apparently, the adventurer's guild was naive enough to give up the information on who fulfilled the request, which is absurd because, even if no foul play was intended regarding the adventurer involved (and they're dealing with adventurers, so they should be familiar with foul play), it enables the client to directly bypass the adventurer's guild and contract the adventurer directly so you can expect that there's no commission there.
In other words, the adventurer's guild receptionist lady (and I expect it has to be her and not someone else because they were able to find Yajin based on his appearance) definitely got bribed by the vice guildmaster. Probably not paid enough by the guild, so she's not putting the profits made by the guild before her own profits. I'd have hoped she was at least neutral since she did give him a pass to get access to the workshops. Actually, did she have to request it from a superior? This wasn't shown, but then maybe someone else got a good look at Yajin, and the reason he was getting this favour, who could have snitched.
considering he just dragged off a guy for blackmailing a benefactor i can only assume he isnt about to do the same thing, so maybe hes actually going to take advantage of the adventurer guilds lackluster enthusiasm to pay mc his dues by promising him a higher payday from now on in exchange for exclusivity
Well, the reason he dragged him off might have been that he wasn't informed of this action (and thus wouldn't profit from it) rather than him having any issues with the action itself; he might very well be fully onboard with coercing an adventurer into giving up their knowledge and then getting rid of them to monopolise it.
We have to hope not because there are actually fully armoured guards present in the room now and the guildmaster is from a noble family so escaping by using force, even without murdering anyone, is not going to end well and he'll have to skip town.
So yeah, I'm guessing he's not actually in too much trouble and that, as you say, he might get rewarded more for this. This doesn't really benefit Yajin that much since he still needs to get requests done to rank up. We'll see next chapter.