qbuild --extract seems to be slightly broken

[jwalton]

$ curl -o MalwareRemover-5.6.1.6.20220729_172738-x86_64.zip https://download.qnap.com/QPKG/MalwareRemover-5.6.1.6.20220729_172738-x86_64.zip
$ unzip MalwareRemover-5.6.1.6.20220729_172738-x86_64.zip
$ qbuild --extract ./MalwareRemover-5.6.1.6.20220729_172738-x86_64.qpkg
./
./data.tar.gz
./qpkg.cfg
./qinstall.sh

gzip: stdin: decompression OK, trailing garbage ignored
./package_routines
/bin/tar: Child returned status 2
/bin/tar: Error is not recoverable: exiting now

If I try this on QPKGs I build myself, I often see it succeed, but then when I try to unpack data.tar.gz it will be corrupt or files will be truncated.