Attached is an area of concern for air leakage into and from the home. The French door bottom corner has been compromised. It appears the door interior members are water damaged and have swollen to a point where the door is warped. There is a visible gap and air felt entering the interior envelope. The initial cause appears to be the exterior seal is broken and rain water has been making its way down through the lower muntin.
Looks to me like the metal cladding on the door is delaminating and needs replacement if repairs and not possible.
It looks like the astragal has been replaced once already, too. It appears time to replace the door.