  We study the $T\bar{T}$ deformation of two-dimensional Yang-Mills theory at
genus zero by carrying out the analysis at the level of its instanton
representation. We first focus on the perturbative sector by considering its
power expansion in the deformation parameter $\mu$. By studying the resulting
asymptotic series through resurgence theory, we determine the nonperturbative
contributions that enter the result for $\mu<0$. We then extend this analysis
to any flux sector by solving the relevant flow equation. Specifically, we
impose boundary conditions corresponding to two distinct regimes: the quantum
undeformed theory and the semiclassical limit of the deformed theory. The full
partition function is obtained as a sum over all magnetic fluxes. For any
$\mu>0$, only a finite portion of the quantum spectrum survives and the
partition function reduces to a sum over a finite set of representations. For
$\mu<0$, nonperturbative contributions regularize the partition function
through an intriguing mechanism that generates nontrivial subtractions.
