I found that the original wing model has some open edges which messes up the print.
Since I am on Linux I can't use the “Fix Model” feature of PrusaSlicer.
I used another Windows machine, opened the model is PrusaSlicer, fixed it and reexported it.
I thought I'd upload it for others and for myself in the future.
The left wings are the original and the right the fixed ones.
The author remixed this model.
Closed some open edges using PrusaSlicer on Windows