Car Coolant Evaporating/Leaking?? Hyundai Kona 2020 2L

Hyundai Kona 2020 2L, 80K km - Low Coolant Level

Last year I noticed coolant levels were low and the coolant cap wasn’t fully clicked in. I thought I must’ve not pushed it all the way in by accident. I took it to a shop anyway to get a pressure test and it came back normal, they topped up with OEM coolant and was good to go.

Fast forward 8 months the same thing, coolant is now close to L and the coolant reservoir cap is not clicked all the way again. I know it was sealed properly before. There is some coolant residue on the side of the reservoir, not sure if that’s always been there or not though.

Do I take it into a shop and get more extensive testing done? Or is this just a cap sealant issue?

As a note - temperatures never go above half on the gauge