The Quid Pro Quo is a serious matter, presently being discussed in the impeachment trial. Did the president use a quid pro quo when he both withheld military aid, and requested an investigation into the activities of Hunter Biden? The Democrats said yes, the president said no.
I think in this particular case involving the Ukraine, we have to go along with the president that there was no quid pro quo. But in other dealings not involving this impeachment business and the Ukraine, it could be a quid pro quo, and there would be nothing wrong with that. Perhaps after the impeachment trial is over it could be called a contingency instead, just to differentiate this from an illegality.