Here are textual evidences of when I 1st verified issue with SHA256SUM from Gpg4win 3.1.16 installation (whose status on my laptop is still T5593 described one).
27/09 20.44.50 C:\Users\'<myAlias>'>sha1sum -?
usage: sha1sum [-c|-0] [--] FILENAMES|-
27/09 20.45.52 C:\Users\'<myAlias>'>sha1sum -help
usage: sha1sum [-c|-0] [--] FILENAMES|-
28/09 4.03.01 C:\Users\'<myAlias>'>sha256sum -?
usage: sha1sum [-c|-0] [--] FILENAMES|-
28/09 4.04.00 C:\Users\'<myAlias>'>sha256sum -help
usage: sha1sum [-c|-0] [--] FILENAMES|-
And here's a bitmap I also took to document issue.