9. By way of derogation from paragraph 8 of this Article, for restrictions to cross-border flows caused by differences in hydrogen blending in the natural gas system, the regulatory authorities concerned may jointly declare that no further action is to be pursued to remove such restrictions. The joint coordinated decision shall be taken within six months of receipt of the information referred to in paragraph 7 of this Article in accordance with Article 6(10) of Regulation (EU) 2019/942 and shall take into account the cost-benefit analysis and the results of the public consultation conducted pursuant to paragraph 6, point (d), of this Article. The regulatory authorities concerned shall review a decision to maintain the recognised restriction pursuant to this paragraph every four years.