Hi,
Are you still looking for a solution?
I have had the same issue for a while now and it turned out to be due to a software called “Buff” I had installed. One of its keybindings was F8 and covered over the controls for FiveM Console, not letting it close when I press F8 again.
Check if you have any form of overlay software or any software really that communicates with the game and has its own keybindings. Check that none of them are or do include F8. This is what solved it for me.
Please reach out if the solution did or did not work, I can try to assist further otherwise.
Regards,