In this situation, does the vertical sign "stopping prohibited" apply also to a soft shoulder?

In the video you are driving along a road outside a town, with a narrow soft (unpaved) shoulder on the right; by the road there is sign B-36 "no stopping" with plate T-25a showing the start of the prohibition, and a line of cars is coming from the opposite direction. The prohibition of stopping also applies to the unpaved shoulder on this side of the road. The answer is: yes.

The Regulation on road signs and signals states that sign B-36 means that stopping a vehicle is prohibited, and the prohibition expressed by this sign applies to the side of the road on which the sign is placed, except for places where parking or stopping is allowed by a sign; plate T-25a under the sign shows the start of the prohibition. The Road Traffic Act defines the shoulder as the part of the road next to the roadway - since the prohibition covers the side of the road, it also covers its shoulder, whether hard or unpaved. So pulling onto the grass or earth next to the roadway does not get around the prohibition, although drivers often think so. The sign is placed where a stationary vehicle would limit visibility or get in the way, for example before a bend or an exit. If you need to stop, you drive on until you pass a sign with plate T-25c ending the prohibition or the nearest junction.

Legal basis: § 28 para. 2, para. 3 point 1 and para. 7 point 1 and § 32 para. 2 of the Regulation on road signs and signals; Art. 2 point 8 of the Road Traffic Act (Prawo o ruchu drogowym)