If the layout follows the schematic, current going to the output on the bottom creates a voltage drop on the trace resistance, which will be measured by U2.

[![enter image description here][1]][1]

It should be routed like this instead, preferably with a note on the schematic. 

[![enter image description here][2]][2]

If U2 is some distance away from SR1, then the two sense lines should be routed as a differential pair. To have the design rule check enforce it, you can put a net tie which makes the two sense lines into different nets from the power traces. This is especially useful if the power traces are copper pours, to prevent the sense lines from being connected to the wrong place.

[Layout around the sense resistor][3] is important for accuracy too.

EDIT:

It would be useful to calculate the resistance of the shared trace:

[![enter image description here][4]][4]

Here's a [trace resistance calculator][5]. I can't see the dimensions, but you can get width and length easily from your layout software, and copper thickness from your fabrication specs.

It should be a good chunk of a milliohm... since your current sense resistors are only 2 mOhm, that would introduce a significant error.

Likewise, since your sense traces do not go to the 2mOhm resistors, but to the power traces some distance away from the resistors, the effective resistance value should be higher than 2 mOhm. So your current sense amps should have higher gain than intended.

Knowing the trace resistance, you can calculate how much error should result (both on the gain and on crosstalk) and check the readings to confirm.

On the prototype board you can cut the sense traces and replace them with hand soldered wrapping wire, soldered directly between the inputs of the sense amps and both ends of the current sense resistors. If that solves the problem, you know what to do for the next layout revision.




  [1]: https://i.sstatic.net/vGyOv.png
  [2]: https://i.sstatic.net/HoxO4.png
  [3]: https://www.analog.com/en/analog-dialogue/articles/optimize-high-current-sensing-accuracy.html
  [4]: https://i.sstatic.net/EdzvY.png
  [5]: https://www.omnicalculator.com/other/pcb-trace-resistance