Quercetin alone without metol provides developers like weak caffenol.

Qu-2
Water(room temp)...........................500 ml
Washing soda,Arm & Hammer (US).....4.5 tsp
or washing soda decahydrate (UK).......10 tsp
Iodized salt......................................0.5 tsp
Quercetin, 2 capsules contents,..........1.0 g

Stir 15 min,filter through cotton wool.
I semi-stand developed APX 100 in this 2hrs 70F, agitate every 30 min.
The negatives are much fogged but strongly stained and tanned.

Qu-3
As Qu-2 with addition of 1 tsp vitamin C.
I developed APX 100 in this 30 min 68F, agitate 10s/minute.
The negatives are somewhat fogged but produce sharp ,fairly fine grained prints.
There is only weak tanning, probably not enough to control highlight density.

Likely the reason why addition of vitamin C speeds up the development is that in Qu-3 it removes the oxidation products found with Qu-2 that tan the gelatin.