  In recent times, astounding observations of both over- and under-luminous
type Ia supernovae have emerged. These peculiar observations hint not only at
surpassing the Chandrasekhar limit but may also suggest potential modifications
in the physical attributes of their progenitors, such as their cooling rate.
This, in turn, can influence their temporal assessments and provide a
compelling explanation for these intriguing observations. In this spirit, we
investigate here the cooling process of white dwarfs in $f(R,T)$ gravity with
the simplest model $f(R,T) = R + \lambda T$, where $\lambda$ is the model
parameter. Our modelling suggests that the cooling timescale of white dwarfs
exhibits an inverse relationship with the model parameter $\lambda$, which
implies that for identical initial conditions, white dwarfs in $f(R,T)$ gravity
cool faster. This further unveils that in the realm of $f(R,T)$ gravity, the
energy release rate for white dwarfs increases as $\lambda$ increases.
Furthermore, we also report that the luminosity of the white dwarfs also
depends on $\lambda$ and an upswing in $\lambda$ leads to an amplification in
the luminosity, and consequently a larger white dwarf in general relativity can
exhibit comparable luminosity to a smaller white dwarf in $f(R,T)$ gravity.
