The constancy of the speed of light is a postulate of SPECIAL RELATIVITY, that it is the same as viewed from an observer in an INERTIAL reference frame (that means an observer at rest or in uniform linear motion relative to the object being observed). Is that clear?
The speed of light is NOT constant in general relativity. The speed of light will differ depending on an observer in a NON-INERTIAL reference frame (that means an observer that is accelerating relative to the object being observed. Is that clear?
Is The Speed of Light Everywhere the Same?
The Speed of Light as Measured by Non-Inertial Observers
That the speed of light depends on position when measured by a non-inertial observer is a fact routinely used by laser gyroscopes that form the core of some inertial navigation systems. These gyroscopes send light around a closed loop, and if the loop rotates, an observer riding on the loop will measure light to travel more slowly when it traverses the loop in one direction than when it traverses the loop in the opposite direction. This is known as the Sagnac Effect. The gyroscope does employ such an observer: it is the electronics that sits within the gyro. This electronic observer detects the difference in those light speeds, and attributes that difference to the gyro's not being inertial: it is accelerating within some inertial frame. That measurement of an acceleration allows the body's orientation to be calculated, which keeps it on track and in the right position as it flies.
When I posted this, I wasn't inviting your stupid opinion regarding the matter. I was educating you about the thing you pretend to know. So, save yourself the embarrassment and keep your silliness to yourself.