Jumper wire on a light switch box and I'm not sure what else
The jumper between switches is fine, but you need to fix that grounding
The jumper carrying always-hot from switch to switch is considered normal practice in the US, but your switches need to be grounded, and because they're mounted to a plastic box, that must occur via ground wires as the switches can't pick up ground from the box.  So, you'll need to use a proper wirenut (one of the 8-port push-in units will definitely do the trick) to bundle all those grounding wires from your cables together with 12AWG grounding pigtails from the green switch grounding screws.