The amount of commercial games that used (and still does actually) Flash is much higher than many could believe. Jackbox is probably one that many here have played in the past few years. Some games used it only for UI, like Borderlands.
A lot of games today use an HTML-powered UI library from Coherent Labs which can still be authored using Adobe Animate (i.e. what the Flash editor turned into): https://coherent-labs.com/
PS At least that was the case 9-10 years ago when I was involved.
Anyways, the client ui team definitely used Actionscript, which I had to read from time to time as a server-side dev.