Can't say i notcied this before tonight so no idea how long it might have been like this.
In the CT at any rate, I loaded the the F4u-1 with 50% gas, but the gauge (only one tank - main) shows 75%, flight time seems normal at the 1.5 fuel burn.
i tested this offline, 25% gas = 3/8 on gauge. 50% = 75% gauge, 100% = 100%gauge.
dunno if any other planes affected this way.