Can soffit vents be blocked by insulation?
They sure can, but they never should be! Stick your head up thru your attic access hole or better yet, climb into your attic (being carefull to step only on your ceiling rafters) and take a look. If you can’t see because of the roof slope, just eliminate any light and you should see light shining up thru the vents from the outside. If you don’t see any then it’s likely they’re blocked. There should always be good air cirulation thru your attic!