Blanka tunnels is an older issue, but under Krnáčová the entire Prague traffic system basically collapsed. There are frequent traffic jams and basically all bridges are in disastrous state.
Libeň bridge, one of the only few Cubist style bridges in the world, has been closed for past two years, Troja pedestrian bridge collapsed last year and just a few days ago it turned out another bridge has to be collapsed and rebuilt from scratch.
Add to that the fact that she called the people complaining about the traffic issues "zpovykaní" or whiners and that adds up to a lot of people not liking her at all.