I have yet to see a PDF that is not displayed in Draw, so that might be a
specific issue you have.
However, here's my experience with it so far: PDF in Draw have always felt
more like a hack than anything. It doesn't seem to handle embedded fonts,
and for fonts available on the system, the rendering is different,
including different spacing between letters. Images and various graphics
elements tend to get out well, but from time to time you'll come across a
graphic that's on the wrong side of a page.
This behavior have been relatively consistent between LO version since PDF
opening was introduced, and to be fair the very nature of a PDF, especially
how the format is laid out internally, makes "opening" them for edition
quite a challenge.
This tool is still useful for some use cases, tough, and I've used it some
times, mainly to extract graphics without losing quality. But it's not a
"PDF editor", at least not yet (obstacles can certainly be overcome, but
that's not what I'd call a priority in an Office edition suite. my 2cts of
course).