Low volume near the end of a base is treated as constructive: if almost nobody is willing to sell at these prices, relatively modest demand can move price. It is the volume half of the volatility-contraction-pattern.
The classic sequence is heavy volume on the decline into a base, progressively lighter volume on each test of the low, and then expanding volume on the breakout. That sequence is checkable and does not require interpreting shapes.
The counter-argument is that low volume can equally mean an instrument has simply been abandoned, and plenty of quiet bases go quieter still. The dry-up only becomes meaningful once expansion follows, which means it is confirmation after the fact.
Related: volatility-contraction-pattern, consolidation, volume-climax, relative-volume, accumulation