The psychology of this debate is fascinating. There are players who no-one disputes are "loyal" and might be then seen to have overstayed their welcome (e.g. Albrighton). There are players that want to use us as a stepping-stone but will have provided plenty of good service whilst here (Mahrez, Maddioson). There are those that fulfil their contractual obligations (Tielemans) but have cost us loads by preventing us getting a fee. Others who sign new contracts, enable the City to get huge fees (Fofana) and are seen as disloyal mercenaries.
It's a quid pro quo arrangement. They are professionals. If the club don't want them or aren't good enough, sod their contracts, they will be sold. If we aren't big enough for them, they'll leave. It's business. Personality seems to play a part, Kante seemed humble and supremely good, and few begrudged his move. Mahrez was/is supremely talented, and wonderful, mercurial player who contributed as much to winning the Premier League as Kante, but is apparently loathed because of his attempts to force a transfer. and his subsequent comments.
Vardy, on the other hand, is considered loyal, the best City signing ever, record breaker, turned down a "big move", but plenty on here want him sent to pasture because he's lost his edge. Loyalty works in mysterious ways.
I'll take four years of mardy Mahrez over 10 years of Andy King any day.