It wasn't soft tissue, it was hard, dried out, but not petrified.
The scientific term is dessicated.
They had to rehydrate the tissue (repeatedly) to actually produce soft tissue.
NOW, let's simplify.
No one seems to have a problem with this mosquito being completely preserved for 40 million years.
“..wasn’t soft tissue, it was hard, dried out..”
oaky, it was un-fossilized soft tissue.