Due to the OTG boost mode’s startup delay, PMID voltage may dip for a short period after VBUS is removed. Check the charger’s corresponding datasheet for the specific timing of the device being used. In general, it is in the range of tens of milliseconds, so the voltage could not be hold up by adding a capacitor.
More information can be found here: https://e2e.ti.com/support/power-management/f/196/t/805621
