Heavy deadlifts, loaded carries, and weighted spinal flexion are the usual suspects when a lower back is irritated. RepRoute's response is deliberately simple: it stops programming them.
Flag the lower back and every exercise carrying the lower_back tag is REMOVED from your plan — 209 of the 219 hinge, carry and core movements (95%), and 248 exercises catalogue-wide. Hinging is all but wiped out (145 of 146 deadlift and RDL variants go), loaded spinal flexion goes entirely (47 of 47), and most carries go too (3 of 5).
Bracing work fares better than the old version of this page claimed. Ten movements survive the flag: Bird Dog, Dumbbell Farmers Walk, Extended Plank, Farmer's Walk, Glute Bridge, Kneeling Plank, Pallof Press, Pallof Press With Rotation, Plank and Push Up to Side Plank. So the plank family and the Pallof press generally stay while the crunch family goes — which is roughly the distinction you'd want, though it's a by-product of per-exercise tagging rather than a rule the engine understands. Check the ones you're given; if a plank aggravates your back, swap it.
Days emptied by that strip get refilled with up to three exercises from the patterns still available — squats, presses, rows. Your leg day doesn't vanish; it stops hinging.
One thing RepRoute does NOT do: reduce the load or shorten the range of motion on a movement before removing it. There is no half-measure in the engine. It's either in your plan or it isn't. If you want a gentler adjustment than that, use Swap during the session on the specific movement that bothers you.