Newcastle's issue isn't so much the price he's been sold for but the way they've dragged this out and ruined the start of their season. If Newcastle were going to do a deal at £125m, this deal could have been done over a month ago and you could have reinvested the money and not gone into the opening 3 games without a striker. Whether the club foolishly believed Isak could be talked into staying or that Liverpool would end up paying considerably more than they have, I don't know but all they've achieved is disrupting the start of the season for you.
I honestly believe that if Newcastle were willing to do the deal when we first approached you, that Ekitike could be a Newcastle player now. It wasn't a coincidence that we made our first approach to Newcastle in the days before the Ekitike deal went through and while I don't doubt that we ideally wanted both, I'm sure a deal could have been done whereby we stepped aside from the Ekitike deal if you agreed to the Isak sale. In the end you've lost Isak, lost out on Ekitike and received a fee well below what you were briefing all summer.