Some cars we’ve seen have the brake fluid reservoir mounted in the frunk, which is sometimes subject to leaks at the hose ends, and others have it mounted directly to the top of the master cylinder to eliminate the connecting hoses.
THAT configuration uses an OEM Volvo reservoir that matches the MC fittings. Either one works just fine, but one is more accessible than the other. To check fluid level some time every other year or so on the top-of-the-MC version you need to remove the front, driver’s side wheel for access. Takes about 4 minutes and you can also do an annual brake line fitting check for leakage at the same time.
It’s not a big deal.