The invention patent of Venus gas energy-saving utility model applied by Junda, patent number: ZL 20 1020 186462.4, can it be used by many companies at the same time?

It depends on the agreement between Xiang Junda and Guangzhou Chuanyu Trading Co., Ltd., and whether there is any provision in the agreement that the patent is not allowed to be transferred to Xiang Junda or Guangzhou Chuanyu Trading Co., Ltd. or a third party can use the patent. Even if there is, it won't. If not, you can, but you should inform the other party of the original agreement, because it is also in his interest. Perhaps the original two parties will sign a supplementary agreement, which will have a clearer constraint on this direction.