In the Loki series, the TVA is hunting variants. Once they capture a variant, they delete the timeline they were found in using a small tool that they put on the ground. The tool then spreads out a purple light that consumes everything it hits and eventually the whole timeline.
But the universe is HUGE. It would take trillions of years for the whole timeline to be reset, if the purple light is moving that slow. So why does the TVA prune timelines like this? if the purpose for it is to stop evil variants of Kang to discover the multiverse and conquer it, pruning the timeline wouldn't necessarily help, as the pruning probably won't even reach him in time.