I’d be very surprised if Porto had done anything wrong here. AFAIK they never accepted Spurs bid, and why would they be locked into accepting an offer that wasn’t favourable to them (add-ons unlikely to activate, not enough money up front which they needed)?
With money, generally. It’s one thing to let 3rd parties know of separate discussions but another thing entirely to let them know of terms. Still, these things move too quickly for clubs to be able to do much about it at the time. Spurs may well look to Arbitration (basically squeeze some money out of us) if they feel they have genuine cause for complaint or they may just put it down to fairly usual transfer murkiness, that they would have been more than happy to have found themselves the other side of!
Throwing it back to you that it’s more likely to help the Salah situation. Mo could well have been waiting for a signal from the club of their ambition to win the top trophies. He may well factor this in to his price.