Unfortunately you (almost**) never get the output on the label.
Like ChrisD5710 & others are saying, the main reason is temperature rise of the panel in the sun, it gets hot & the output drops.
** if the sun pops out from behind some clouds on a cold day you'll get better numbers for a bit until the panels heat up again.
A typical panel's output drops like this:
Temperature coefficients of Pmax = -0.40%/?
Temperature coefficients of Voc = -0.30%/?
Temperature coefficients of Isc = 0.06%/?
So if the label spec is at 25degC (called STC) & the panel runs at 45 degC (called NOCT, might be hotter at your place) then 20 x 0.40% is 8% less output power right there.
Re the wiring, you've got a 10m run of AWG16 cable which has a resistance of about 0.0132ohms per m (from an online look-up chart).
The total "round trip" length is probably about 23m (bit extra at panel end?) so 0.0132 x 23 = 3.036 ohms at 25degC
The cable losses are from current & go like this:
so Imax = (0.56A x 4 strings of panels) = 2.24A at 25degC (ie STC)
so at your place assuming 45degC operating temp it's 20 x 0.06/100 = 1.2% less current = 2.21A (ie at NOCT)
So on your cable with 3.036 ohms, at 2.21A current you're getting about 0.67V loss which is not much vs about 32.45V (see below) ie that's about 2% loss of voltage.
Now some voltage numbers:
Spec says 17.83 max power voltage at 25degC test conditions
Assuming the MPPT unit tracks this properly....
At 45degC operating temp the max power voltage drops by about 8.9% (typical panel spec sheet STC vs NOCT)
So each of the 2 panel strings should be putting out about 17.83 x 2 x .909 = 32.45V at the panels
At 2.21A, you'd see about 32.45 - 0.67 = 31.78V at the controller
So expected power would be 2.21A x 31.78V at the controller's input = 70.23W
You've got a 7s Li-ion battery so assuming full voltage = 7x 4.1V = 28.7V, that's only about 3V difference to the controller's input?
From the controller pic, your numbers look close to this but voltage is up a little & the current a bit down.
The MPPT unit may tracking a different point or not able to pull enough current from the panels with only a small voltage difference?