Every liberal does it too, from center right radlibs to far-right "conservatives": the most extreme right fringe liberals hate the mainstream liberals for not being bigoted enough, the mainstream libs hate the radlibs for not being cruel enough, and the radlibs hate the left for not being chauvinist enough.
Denouncing chauvinism in particular is like a liberal moral event horizon, a cardinal sin against their self-interested belief in the righteousness of the imperial hegemon that keeps the treats flowing at gunpoint.
The "don't let perfect be the enemy of good" refrain was used by left-libs in the context of policy debates like Sanders' healthcare plan vs Warren's. I'd argue that while leftists and left-libs agree on many policies, the differences in what is considered feasible and acceptable (for instance in the 2020 primary, backing Sanders vs Warren) stem from a few ideological differences.
I agree with this. The liberal that feels cognitive dissonance when encountering leftist ideas is on the road to becoming a leftist.