Steps to reproduce:

1. Upload a zip file whose file name contains spaces
2. Select "Extract into new folder"
3. Observe in JCR browser, the top folder node created with spaces in its node name.

These spaces should be replaced with dashes.
https://documentation.magnolia-cms.com/display/DOCS/Managing+pages#Managingpages-Characterrestrictions

Note: files and folders with spaces inside the zip file are not affected and are correctly sanitized, regardless of extract location.

Additional quote via MGNLDAM-788:

It does result in asset links in which the spaces are not correctly escaped. Most browser don't have problems with it, but for instance Facebook does, so in our case the opengraph image is not retrieved.