My Zephyrus turns off randomly

Hello everyone,

I have my zephyrus for some years now, I don't remember how long exactly but i think for about 3 or 4 years.

I use this laptop for everything but mainly for gaming, the charger is permanently plugged in when playing which can sometimes be for long period of times (12+hour). Recently, it started turning off in the middle of gaming.
From what i have found, i think it is a battery issue, even though it is charging, the PC is always at 0% (started recently) as shown in this screen

https://preview.redd.it/5tk78sfks6ag1.png?width=375&format=png&auto=webp&s=56a6a1631e52c9b5b8d43002a485dfb6346171c1

I don't really know how to check the battery health status but i think it might be really bad otherwise i wouldn't have this issue ?

Does anyone know how to check what is wrong? I already did a full MyAsus scan and nothing was wrong.
If the battery is indeed dead / close to dying, how can i find the original battery to buy and how much would it cost me to buy it + find someone to install it ?

My PC is a Zephyrus G14, this is the model : GA401QM.415

Thank you for taking the time to help ! :)