The KE can be different in different frames of reference.

With respect to the stationary frame Oxy the KE is $\frac34 mv^2$ as per your calculation.

However, points C and P are moving relative to the frame Oxy. For example, C is moving with velocity v in the +x direction, so in the frame Cxy in which C is stationary the disk has no translational KE, only rotational KE. The total KE in this frame is $\frac14 mv^2$. The angular velocity $\omega$, and therefore also the rotational KE, are the same in all non-rotating reference frames.

The instantaneous velocity of point P in the frame Oxy is $\frac12 v$ in the +x direction, because P is half way between C (which has velocity $v$ in the +x direction) and the point of contact with the ground (which has velocity $0$). In the inertial frame Pxy which has the instantaneous velocity of P, the disk has velocity $\frac12 v$ and translational KE of $\frac12 m(\frac12 v)^2=\frac18 mv^2$. It still has rotational KE of $\frac14 mv^2=\frac28 mv^2$ so the total KE in this frame is $\frac38 mv^2$.