If you are downed and rejoin server, you aren't down. It can be really badly abused, and literally never die.

What mods are you using? What minecraft version? What server platform? Normally this does not happen. You will die if you leave.

I'm playing on 1.19.2. I've been using 2 different hosting platforms, it was ServerCraft before and now it's EnderChest, the same issue on both. After you leave there is a chat message about your death, but you spawn on your body like you've been rescued. I attached mod list in a file.
mod list.txt

In 1.19.2 there are issues with FirstAid and Mohist. Unfortunately I do not support 1.19.2 anymore. I cannot help you there, sorry. They only way to fix it is to get rid of the incompatible mod/ server architecture.

Do you do commisions? If yes, how much would it be for fixing my issue?

It's not easy to fix and I doubt it is worth. Rather consider updating.