Thanks for that old bug report. We fixed it soon after you reported it, 
here:

https://git.savannah.gnu.org/cgit/gzip.git/commit/?id=63aa2268a5abfed0116d04bbe3952e4a753af91d

but didn't make the connection between the fix and the bug report. So 
I'll close the bug report now.

By the way, I just now tried bleeding-edge gzip on macOS 12.1 (Apple M1) 
and found one portability glitch, which I fixed by installing the 
attached into gzip.