Is it illegal for others to use my patent before my patent application is made public?

It's not infringement, because your application is not open and not authorized.

Unauthorized, that is, you have not obtained the patent right, so there is no infringement.

If it is made public, there will only be the possibility of infringement, just "can ask for it" and "pay appropriate fees." The implication is to discuss with others: "you may infringe, give me some money." (Because there is no authorization and the scope of rights is not determined, it is difficult to judge whether the other party is infringing)