I have never seen a door set with that big of a gap unless it was to get past floors that were not level.
Space between door and floor.
Gaps between door casing and laminate flooring are common and manufacturers have designed a wide variety of special pieces for this purpose.
You simply describe the gap take a picture of it or.
Transfer this measurement to the threshold put on a pair of safety glasses and cut it to this length with a hacksaw or jigsaw.
Door clearance although this is a broad term it usually refers to the space between the top of the door and header rabbet or bottom of the door and finished floor.
During installation of a frame and during the initial formation 1 2 cm gaps should be left for foaming.
It should be measured from the floor surface to the bottom of the door.
Between a leaf of interior doors and the floor it is required to leave a gap of at least 2 2 5 cm to provide natural ventilation.
If each room has individual air returns the numbers can be smaller for personal taste.
To fix the issue the doors need to be removed bottom of the jambs cut and reset the door.
This allows for proper air exchange between rooms.
The standard i use is 1 2 over finish floors 3 4 is acceptable.
The door gap to the floor should be 5 8 to 3 4 inch.
That is a lot of room for unlevel you have there.
Measure the distance between the door frames at the floor.