Carrier signal - Dual Sim (ESIM)

Hi fellow Iphone users. Hoping you can help me resolve my issue. I am using an XS MAX with dual sim - esim and physical sim.

Signal is fine for both standy but when i use my ESIM to call, i notice that the signal for the physical sim decreases until 0 bar is showing. Immediately after i finish my call, signal is restored to that physical sim - full bar.

Is this normal or is there something wrong with my phone?