This is an obvious indication that FiveM/Cfx.re is having issues with their client authentication service.

Live status for the client authentication service can be found here, among other essential services that FiveM/Cfx.re operates, should they have issues too.

Q: Can you fix this issue?

A: We can't solve this as we're not the developers of FiveM/Cfx.re - it's simply not our responsibility.

Q: How can I fix this?

A: You can't. No one can solve this error except for the developers of FiveM/Cfx.re - wait patiently until they do so.