While staying at a BiL’s huge place in France, I was once making an ample potato salad for a big alfresco lunch party he was holding. There was hardly any mayonnaise, so I said I was nipping to the local supermarket for some.
Another BiL, a very Francophile foodie, honestly nearly had a heart attack at the idea of bought mayonnaise! He insisted on making some instead, and I don’t know what he did or didn’t do (he’s usually a very accomplished cook) but it was horrible, just oily and tasteless, and so much of my potato salad* which usually vanishes PDQ, was left and ultimately thrown away.
I usually add a little lemon juice, plus S&P and snipped chives or the green of spring onion, with any good quality mayonnaise - and only just enough to bind it.
Needless to say, another time I’d insist on doing it my way, whether he threw a fit or not!