Who is advancing and taking cities? If an invader supposed to do that, the failure to do so means they have not only stalled but where they have been pushed back means they are losing.
This is especially true when a Nation like Russia is supposed to dominate the Eastern European region. When it cannot do this, it is because it no longer has the strength to do it.
Unless you want to say Russia is not serious about winning?
If you call taking undefended open ground as winning, okie dokie.
If you call taking Liman/Lyman winning at the cost of huge numbers of Ukrainian lives winning. Okie dokie.
Winning or losing: both come with measurements.
And as long as the war/conflict carries on, those measurements remain fluid.