JPEG file padding

[thorsted]

Over the last year or so I have come across a few examples of JPEG files which have padding after the 0xFFD9 marker. Some are a few bytes while others are megabytes in size. Seems to be a bug in some downloading software.
See https://www.macrumors.com/2020/05/01/macos-jpg-truncation-bug-widespread/

Also a conversation on the subject here:
https://twitter.com/CHLThor/status/1311728118411849728

I have noticed some JPEG signatures have 65k of maxbyte offsets, while others have 130k.
fmt/44 is looking for 65536 maximum offset
x-fmt/390 is looking for 16000 maximum offset
x-fmt/391 is looking for 131072 maximum offset

Questions:

• Should 0xFFD9 marker be optional for identification?
• Should the max offset be consistent?

See also Samsung trailer makernotes:
https://exiftool.org/forum/index.php?topic=10813.0