Same thing over here pretty normal for brakes to hold on for a second after you let go.I experience it in normal mode but not in sports mode. I thought it was normal. Our brakes do make noise when cold which is normal, if noise is loud and more like a thump then something might need grease. It happened to me when I installed my brakes and rotors. Found the noise and greased it, it never came back.
Standstill decoupling is enabled by default in sport and comfort on the Supra.I haven’t found details on how this is programmed for the Supra. I notice the behavior in Normal mode, but not in Sport, which intuitively makes sense. This may be what you’re experiencing rather than the brakes grabbing or delaying release.