This also depends on the specific case itself, because there is no detailed patent information about this case, so I can only summarize my personal point of view theoretically: if softness is necessary, if softness fails to meet the requirements and cannot solve the technical problems, then the exclusive right is the lack of necessary technical characteristics, and the patent can be declared invalid according to the provisions of the second paragraph of Article 20 of the Detailed Rules for the Implementation of the Patent Law. If even if there is no softness, other technical features in the exclusive right can add up to solve the technical problem that the inventor wants to solve, then softness is not a necessary technical feature to solve the exclusive right problem, and it does not belong to the lack of necessary technical features.
For the issue of full disclosure (Paragraph 3 of Article 26 of the Patent Law), it means that the instructions should be made public to the extent that ordinary technicians can implement them. If softness is indeed a necessary feature in this case, and the manual does not explain it, then you can use the second paragraph of Article 20 and the third paragraph of Article 26 of the Detailed Rules to declare it invalid.
Depending on the case itself, it is necessary to make invalid suggestions and find a professional institution. The above is for reference only.