The client has been a member since Oct 31, 2022, so it has been just 21 days. The question that needs to be addressed is whether any freelancers were interviewed for those 38 open jobs and for long such jobs have been open and whether those open jobs are totally different from one another.
A system that limits the number of job posts from clients could be implement.
A good solution is a slot system: New clients have 1 slot to post a job, if he hires, he gets 1 more slot, then he can post 2 jobs. Iff he hires on these 2 job, he gains more slots, he can post 4 jobs now, and so on... Until a max limit of 10. I realy doubt that a client can manage 10 projects. 10 job posts is well enough for any client.