If it's him it's because he probably realized that roster has no actual hopes of winning a world series.
Look at it this past season; it was basically Judge, Soto and an above average but not what he used to be Stanton powering that offense. Come the postseason, Judge disappeared off the face of the earth and was only saved from scorn by the fact Stanton decided to turn back the clock 10 years and retook his once MVP form. Without that, there's a good chance the Yankees don't even get past Kansas City in the ALDS.
The sons don't like to spend their money like daddy did. If Soto signs, who says they go out and grab anyone else? It would probably be on him, Judge and a declining Cole to win it on their own.
Now, the teams in pursuit of Soto aren't exactly guarantees either but a team like the Mets will absolutely throw money around to put a team capable of winning it all around him. Uncle Steve wants his world series, no matter the price.
If it's the Yankees the answer is simple; The Steinbrenner sons aren't like his dad and are cheapasses. Sure they paid Judge, but if they didn't, the fans likely burn down Yankee stadium and come looking for him. Soto not so much.