Here is my test case in my Windows OS:
$ cd dist && bestzip . ../dist.zip
$ cd .. && unzip -l dist.zip
Archive: dist.zip
Length Date Time Name
--------- ---------- ----- ----
1468928 2021-08-06 04:53 ./build/Release/libglib-2.0-0.dll
289792 2021-08-06 04:53 ./build/Release/libgobject-2.0-0.dll
21130752 2021-08-06 04:53 ./build/Release/libvips-42.dll
343040 2021-08-06 04:53 ./build/Release/libvips-cpp.dll
360448 2021-08-06 04:53 ./build/Release/sharp.node
103780 2021-07-31 05:17 ./fonts/Barlow-Italic.ttf
98340 2021-07-31 05:17 ./fonts/Barlow-Regular.ttf
181 2021-07-31 05:17 ./fonts/fonts.conf
132740 2021-07-31 05:17 ./fonts/SourceCodePro-Regular.otf
889623 2021-08-06 04:53 ./index.js
2563398 2021-08-06 04:53 ./index.js.map
40682 2021-08-06 04:53 ./sourcemap-register.js
1490 2021-08-06 04:53 ./vendor/8.10.6/include/vips/vips8
1468928 2021-08-06 04:53 ./vendor/8.10.6/lib/libglib-2.0-0.dll
317662 2021-08-06 04:53 ./vendor/8.10.6/lib/libglib-2.0.lib
289792 2021-08-06 04:53 ./vendor/8.10.6/lib/libgobject-2.0-0.dll
84632 2021-08-06 04:53 ./vendor/8.10.6/lib/libgobject-2.0.lib
21130752 2021-08-06 04:53 ./vendor/8.10.6/lib/libvips-42.dll
616376 2021-08-06 04:53 ./vendor/8.10.6/lib/libvips.lib
11 2021-08-06 04:53 ./vendor/8.10.6/platform.json
4230 2021-08-06 04:53 ./vendor/8.10.6/THIRD-PARTY-NOTICES.md
580 2021-08-06 04:53 ./vendor/8.10.6/versions.json
--------- -------
51336157 22 files
And open with 7zip, also contains ./ directory:

Seems it's a issue only run in powershell or cmd, when I run in msys2 or cygwin, it's OK.
Here is my test case in my Windows OS:
And open with 7zip, also contains

./directory:Seems it's a issue only run in powershell or cmd, when I run in msys2 or cygwin, it's OK.