As noted above - not a mystery. Cloud vs. local execution.
Smart Lighting will almost certainly go away next year with the Groovy infrastructure shutdown.
Optimists will hope that eventually Automations will execute locally. Or the new Rules API will execute locally. Or some other front end that replaces them will have rules that execute locally.
Pessimists will note that SmartThings has been promising more local execution for 5 years and hasn’t delivered it at all. And everything that they have introduced to replace existing functionality has been sorely lacking in many ways.
(Realists will simply buy a Hubitat hub and move on)