Not technically a bug, but unusual behaviour.
When you run and do a knee-slide into a car or barrier, if you have any excess momentum, you will ricochet and your excess momentum can carry you beyond cover.
I think that when you slide into a barrier, you should stop - no matter what the angle of the barrier is to you.
The slide should be terminated when you hit the barrier (green slide) and you should NOT continue to slide out of cover at an angle (red slide) like you are on a ice rink.