Yes. The interior light is part of the heating element, which cycles on and off during normal operation. The light turning off mid-cycle is not a malfunction.
Fix: No fix needed. This is normal behavior. The unit is still cooking and heating when the light is off.
If that didn't work: If the control panel also turns off or the cooking stops entirely, you have a different problem. Check the power cord for damage and ensure the plug is fully inserted into a working outlet.
Heads up: Do not look directly into the interior light for long periods. It's bright and connected to the heating element.