https://www.underhoodservice.com/hyundai-kia-hybrid-drivetrain/
The site seems aimed at Repair Technicians, rather than the general public and the author claims to have some technical accreditations. Obviously, I have no idea if the information is actually correct, or if it applies equally to all Hyundai/Kia Hybrids - but it says :-
Andrew Markel wrote:The instrument cluster displays the state of charge as a bar graph with L indicating 30% charge and H indicating 80%. It is not an indication of the Actual HEV Battery. SOC must be viewed with a scan tool that can access the HCU module.
(SOC=State-of-charge)
Having failed miserably in my attempts to physically access the HEV battery ... and without a dedicated Hyundai Scan Tool, it's hard to verify. (My generic Scan Tool can see modules other than the ECU and Transmission, but nothing useful has issued forth so far )