Have legendary stardust rewards increased?

The practical effect is on Awakening Potential, which runs on Star Dust, Star Sand and Star Essence. More stardust per legendary means fewer repeat runs to feed that lane. It does not finish an awakening on its own, though. Stardust is one input of three, and the other two did not move with it, so your awakening pace still bends to whichever of the three you are shortest on.

Everything else in the upgrade economy is untouched by this. Resources you gather get split across several separate upgrade systems, and a buff to one feed does not lift the others. Resonance upgrades, the ones that ascend an Aniimo past a specific level cap, run on Dewdrop Crystals and are unaffected. Upgrade materials are limited across the board, so plan allocation rather than assuming the extra stardust buys you slack somewhere else.

Do not confuse this with legendary tokens, which are a different resource entirely. Those come from open-world exploration, catching, and main story progression. The usual warning still applies to stardust: spending rare resources before you understand where each upgrade system pulls from is how people end up with a half-finished awakening and nothing left to push it. If you are early and unsure, hold the stardust rather than dumping it into the first Aniimo you like.

Not settled: The size of the increase is not attached to a number anywhere in the build, so you cannot budget an awakening around a specific per-drop figure.