I have one Inkscape document I am working on. I wanted to add a vector graphic into that document from https://bioart.niaid.nih.gov/bioart/4 (also attached).

So, in my Inkscape document I imported the vector graphic. But I found that the stroke of certain elements of the vector graphics appear to have randomized themselves.

I could replicate this by downloading and opening the vector graphic in Inkscape, then copy and pasting into my document:

I cannot replicate this in a fresh Inkscape document. After deleting all the elements in the Inkscape document I had trouble pasting into, the issue still persists. I've attached that weird document here.

For now I can hotfix this by copy-pasting the entire contents of my document into a fresh one. But what's happening here?

The well-plate graphic was made in Adobe Illustrator and uses CSS classes for style (fill, stroke, etc.).

Importing brings in the css classes and they get scrambled up. Inkscape is usually pretty good with those, but not always.

Pasting a copy converts the class style info into inline attributes, and that seems to work better.

The weirdo document should be discarded. Even after deleting the objects and cleaning the document (menu: File>Clean Document) there are remaining css classes that could interfere with new objects using classes.

Thanks! Your explanation makes a lot of sense. I guess for now I'll report this as a bug at the gitlab.