You should not be vetoing trades in a league as commissioner unless it is VERY clearly collusion.
This trade, on paper, looks pretty awful and lopsided in favor of drake. But maybe she needs that RB in the current year and is desparate enough to accept it. At the end of the day, it is not your duty as commissioner to protect people from their own bad decisions. Everyone in the league is probably just upset because this dude is a low baller and finally got someone to bite. If any one of them had that same offer on the table, none of them would hesitate to accept it so end of the day, its just people being mad about missing out on a steal / opportunity.
You need to let the trade go through, it’s her own fault for not doing the proper diligence. What I would recommend you do though as clearly she will have a target on her back now going forward, is to maybe provide some counselling and let her know of resources to use before considering lopsided trade offers. Or just simply tell her to shoot a message out to the league to get inputs and thoughts before accepting a trade. Not only does this create more trading activity, it’s just a means of setting a market for the highest bidder.
I personally do not believe in trade vetos and hate league trade votes even more. Everyone will look out for their own interest so legit trades will often get turned down just because they are sad they missed out on the opportunity. Which is stupid in my eyes.