The Renaissance revival in Regency style
Though the prime inspiration in Empire and Regency styles was the Roman and Greek antiquity, there are also elements of a Renaissance revival going on. Which is interesting, as the Renaissance itself was a revival of the Antiquity. So this style is double-quoting historical sources, so to speak.
Paned/puffed sleeves, standing collars and bold colours is typical for this style. There can also be references to historical portraits in pose and background.