When saving a document with vector layers hidden, on reopening this document all vector attributes (line color and surface color) varnish on hidden vector layers if I make them visible again.
Windows 10
Krita 4.1

What seems to be happening is that after reloading the hidden vector layers do not have their projection calculated, and this still doesn't happen on show. The actual data itself is left alone, but you need to select the shapes with the shape selection tool and move them to force an update. Please report a bug at bugs.kde.org under the product Krita, so we can track this bug.