[Sequoia] Battery indicator does not detect battery drain whilst laptop in standby or turned off

I have a Macbook 12 (2016) running Sequoia - everything works well except the battery percentage indicator.

I swapped in a third party battery and it holds a decent charge and the MacOS battery % drop as expected from a full charge when using the laptop uninterrupted.

But when I turn the machine off and leave it unused for a week or two, when switched back on it seems to just "remember" whatever % it was last on and not account for charge lost whilst switched off.

So it might say "89%" and drain from there as I use it but then just shuts off all of a sudden without any warning once the battery is fully depleted.

I tried recalibrating the battery as per the official recommendations (charge, use until drained, recharge and keep charging at 100%) but to no avail. I used to have this issue first when putting the laptop to sleep and it just not registering drained charge whilst in sleep so now I always shut it down when I'm done to see if that helped but the issue remains.

Any tips what else I could try to diagnose/fix the issue? Or any third party tools that might help detect the "true" charge of the battery despite what MacOS % thinks?