Sliding doors overlap which is a more efficient design and creates a tighter seal where as french doors come together with no overlap and an increased chance for air infiltration.
Less air leakage at sliding or swinging door.
If you cannot re create the leak problem inspect the interior of the door for stains or.
Occasionally these sliding doors leak and need to be repaired.
Sliding glass doors are less secure security wise and more prone to greater maintenance needs mechanical problems sliding problems locking problems etc.
Look at nfrc labels to find air leakage ratings.
Aim a garden water hose with a sprayer set on mist or low at the outside of the sliding door.
A door with one fixed panel will have less air leakage than a door with two operating panels.
Common leak paths for doors.
It may seem obvious but a door left open or one that cannot be closed tightly because of wear and tear is a significant problem during a storm.
Also as winds blows against a french door it tends to bow thus causing additional air leakage.
That design avoids two swinging doors that seal to each other in the middle which can leak air as it ages.
When buying or replacing patio doors swinging doors generally offer a tighter seal than sliding types.
Hinged doors are more energy efficient in regard to air infiltration and exfiltration more air will leak under and over a sliding glass door than around a hinged swinging door.
Sliding doors overlap which is a more energy efficient design and creates a tighter seal.
However french doors come together with no overlap and an increased chance for air infiltration.
Hinged doors leak a lot less air than sliding doors.
The best hinged door option is a single swinging door and one or two large insulated glass panels next to it.
Spray the door and look for the leak location.