There have been rumors since he came to the Clippers about the outside the cap benefits Kawhi got like a paid-for luxury apartment. I assume those rumors were mainly from lakers fans mad he didn’t choose them, but there’s been smoke about under the table stuff with him for years.
Being reminded of some of the stories from back when Kawhi signed with the Clippers. He and his uncle were demanding illegal sponsorship deals from teams during the free agency process. Jeanie Buss claimed she refused those requests and that was why he went elsewhere (her Dad would have named the Forum Club after him).
The Raptors owner complained to the league about this at the time but they never did anything. He says he met Kawhi’s demands for $15m in sponsorship deals (that the team had to facilitate), but he left for the Clippers anyway. Imagine an owner complaining to the league that he tried to cheat to keep a player but someone else cheated more. That’s why everyone was speculating at the time what he took to move to the Clippers.
ETA - here is a link to one of the reports from back then (well it’s a blog about the report, but the original Sam Amick report is paywalled so it has some of the relevant quotes):
Los Angeles Lakers owner Jeanie Buss reportedly refused Los Angeles Clippers forward Kawhi Leonard's uncle's illegal requests during 2019 NBA free agency.
lakersnation.com