The shroud has a side strip that is 3.5″ wide that runs the entire length of the cloth. So, the shroud was cut at one point in time and then the strip was sewn back onto the main cloth. You can see the side strip on left side of the cloth below:
It is evident it was originally one piece of cloth in the transmitted light photo:
It is a complex seam attaching the two cloths:
Figure 1 (below) shows a portion of the x-radiograph of the section of the Shroud’s frontal image displaying the end edge of the side strip, the missing panel with the exposed backing cloth, and the seam between the strip and the rest of the Shroud.
https://www.shroud.com/adler2.htm
The seam attaching the cloths are consistent with a seam found in the 1st century at Masada.
Dr. Flury-Lemberg found the cloth’s finishing, at its
hems, and in the joining seam to have been done using an unusual type of stitching
very nearly invisible on one side, and as such closely resembling that of ancient
Jewish textiles as found at Masada, the Jewish palace-fortress that was overthrown by
the Romans in AD 73.
https://www.shroud.com/pdfs/n51part2.pdf
There are many theories proposed on why it was cut, but the one that makes the most sense to me is the one proposed by John Jackson. He theorizes the shroud was cut at the time of burial and the side strip was used to wrap around the entire body and the shroud.
This theory also explains why John mentions there was more than one linen cloth.
John 19:40 (KJV)
Then took they the body of Jesus, and wound it in linen clothes with the spices, as the manner of the Jews is to bury.
https://simple.uniquebibleapp.com/bible … /19#v19_40
Based on the Masada seam, the two pieces were most likely reattached sometime in the first century. Additionally, it must’ve been reattached early in the history of the cloth because the water stains and creases affected the entire shroud.
https://debatingchristianity.com/forum/viewtopic.php?p=1119872#p1119872