DIAGNOSIS Streaking is usually a deck height or leveling issue, not a blade sharpness problem. One side of the deck is lower than the other, so it scalps the ground while the high side misses grass tips.
FIX Check the deck level. Place the mower on a flat, hard surface. Measure the distance from the ground to the blade tip on the left and right sides (with the battery out, obviously). They should be equal. Adjust the height lever to a middle setting, then check if all four wheels are clicked into the same notch on their individual adjustment rods. A wheel can pop out of its notch, throwing everything off.
IF THAT DIDN'T WORK The blade might be installed upside down or it's the wrong blade. The Toro Recycler blade has a specific wing design that lifts grass. If it's flipped, it won't cut cleanly. The writing on the blade should face toward the deck.
HEADS UP Mowing too fast, especially with self-propel, can cause streaking because the blade doesn't have time to suck grass up into the cutting chamber. Slow down your walking pace in thick grass.