OK, got some context for this from Alpinestars.

Apparently, Marquez is using leathers with the old style fastening. They were fine on the Honda, but Astars ask Ducati riders to use the new style fastening, which is more sturdy.

Different airflow behind Ducati fairing... https://t.co/ZwKeuruVcF

— David Emmett (@motomatters) March 11, 2024