Local boundedness for solutions to parabolic double phase problems

In this paper, we investigate the local boundedness of weak solutions to parabolic double phase equations of type $$u_t-\mathrm{div}(|Du|^{p-2}Du+a(x,t)|Du|^{q-2}Du)=0\quad\text{in }Ω_T:=Ω\times(0,T),$$ where $0\leq a(\cdot)\in L^\infty(Ω_T)$ and $\frac{2n}{n+2}<p<q<p\left(\frac{n+2}{n}\right)$, so