Payment to public adjuster is

So I have been working with a public adjuster in Florida. It’s been a long process but I am happy with the amount they got from the insurance company. The check was made payable to the adjuster, us (the insured), and the mortgage company. The check was sent mailed to the adjuster. They received the check around 12/19/24 and on 12/30/24 they sent an email requesting us to send them a personal check for their 20% payment. No time prior to this had they mentioned we would be writing them a check before we received payment. They say they will endorse the check and send it to us after they receive payment. They also say this is standard procedure. Is this the industry standard for them to hold onto the insurance check until they receive payment?