Is the driver of a tractor unit with a tanker driving in the left lane obliged to allow the vehicle in front of you to change lanes to the adjacent one?

Why?

The right lane used by the car ahead does not end at this point; the sign indicates a narrowing farther ahead. The zipper merge obligation applies immediately before the lane ends when traffic has slowed significantly, so the tanker driver is not yet required to let that car merge here.

art. 22 ust. 4a Prawa o ruchu drogowym