It's not surprising that Trump has such insecurity and greatly fears the "threat" that Governor DeSantis poses. After all, he, like all of us, observed the actions taken by Governor Desantis over the last 6+ years and his meteoric rise in popularity, not just in Florida, but nationwide.
Trump observed DeSantis doing what he failed to do, and securing elections in Florida, where DeSantis and Republicans across the state won their elections in landslides that actually reflect the true sentiment of the majority of the population when the rigging factor is removed. We are a conservative country and Florida is a conservative state. We saw true numbers reflected in the 2022 midterms in Florida.
Trump also observed DeSantis making Florida a refuge from COVID tyranny. People from lock down states made Twitter and other social media posts, essentially in awe of how Floridians were walking around grocery stores and other public passes without masks. Florida was one of the few escapes from COVID tryanny, one of the few states with a sense of normalcy.
I suppose Trump also observed as DeSantis enacted real concrete legislation to remove CRT from schools, to end Disney's autonomy, thereby putting a stranglehold on their twisted grooming, and to put an end to perverted drag shows for children.
No wonder Trump is hurling false allegations and assigning childish nicknames to DeSantis. He's the schoolyard bully after all. Sensible people wouldn't expect any less from DJT.