I believe they are palm leaves and a reference to the carpet in Emile Hermes’ office where the carriage is displayed

but yeah I wouldn’t have gotten it at all had I not read about it.
Full blurb from H.com -
The story behind
The phaeton, named after the son of the solar deity in Greek mythology, is a horse-drawn vehicle that was popular in the late 18th century in France and England. Lightweight and easy to handle, it allowed the driver to move swiftly around town. Here, the designer Pierre Marie presents a rear perspective of the model in the Émile Hermès collection, with its large wheels and delicately painted decoration. Around the scarf, framed by harmonious curves, a pattern of palm leaves recalls the rug in Émile Hermès' office, where this precious carriage is displayed.