that seat material looks like the older Repop stuff from the late 1990s before they started to stamp them with the fake comfort weave pattern that the concourse guys went nuts over.
i don't know the history with your car but that seat material isn't original.
the photo of the back of the drivers seat has white plastic clips in addition to the hog rings holding the seat material on.
my original seat material did not have these they just used hog rings to hold the seat material onto the frames.
this would also lead to the seat material being a early replacement covering offered a few years ago.
now most people when they swap the seat covers forget to take the seat badges off the front seats, in your case they did remove the seat badges and place them on the replacement material.
to dig deeper you would need to pull off the seat covers and inspect the area behind the seat badges.
ford originally punched the badge through the vinyl then put a backing plate and hot riveted the badge studs holding it to the backing plate.
when the seat covers are replaced most guys will unthread the material in the center where the badge sits, insert the badge with backing plate then by hand restitch the material. you will be able to see this repair on the backside.
another method is cutting the backing plate popping the rivets out and then you can get away without restitching things but the backing plate will show a repair was done.
cheapest method is they pull the backing plate completely then drill a hole in the studs of the badge and hold it to the seat with a knot, or they glue the badge to the material, but usually it comes off.
they never made reproduction seat covers with the badges so the reproduction will always show a repair behind the badge.
the deal with the tags on the seats:
the tags are part of the seat frames so they never touch those. they are suppose to have the part number and a small piece of sample material attached to them.
sometimes the badge is also painted to the original interior color.
so for example my car is originally red vermillion interior: when i striped my seats down i found the original tags were also painted Red and they had a small piece of vermillion attached to the part number tags.
the tags were also painted red as were my front seat tags and the lower seat frames were also painted red.
I converted my car to black interior
so i took the seat tags off, repainted them black and cut a small piece of extra seat material in black and hog ringed them back onto the seat frames.
I also sand blasted my seat frames repaired cracks and broken springs and spray painted them Black as well.
then i rebuilt the seats back up using musklin and canvas like original I even went as far as recreating the canvas with wire insert supports like original that held the foam in place on the seat bottoms.
took me 3 weekends to rebuild all 3 seats in the car and i used all reproduction parts except for the seat backs and the chrome front seat release levers.
you would swear my seats are original to the car but they are not and a good eye can see the comfort weave is fake as well.
I also replaced all the original red pieces in my interior that were all ruined with new black interior pieces, Don at Ohio sold me the rear quarterpanels that i used.
Also at the time, i did not have the Front metal seat badges on my car, both my originals were long gone, i had finished the front seats and just ignored the missing badges.
5 years later a mustang club member gave me seat badges from seats of old junk, he just cut the badges off the seats so they had original comfortweave material behind them.
i did nothing with them for about a year because i was scared about how to install them. I figured out by carefully cutting the backing plates i could make it really easy and require no stitching, i had both badges installed in less then 3 hours.
So it was kind of funny that it took me like 6 years to finish my front seats.
but now if you pull my seats out , the tags even look correct on the surface, unless you read the part number, which states they are suppose to be red vermillion