Q.burning bush not bright
Dwarf Burning bush not bright for 2yr plant in full sun, west facing, zone 7, SE Pa. Planted dwarf euonymus 2 yrs ago and they are growing but color in fall is dull purple.

Optimize the Burning Bush growing environment. Full sun and regular watering weekly, more during dry spells.
Providing a light fertilizer early in the spring can help improve plant health.
Environmental conditions certainly can effect the plants color and condition.
I myself have one shrub that has been red for a week and one shrub that is very slow to turn this fall.
Here is a link to refresh you on the care requirements.
https://www.gardeningknowhow.com/ornamental/shrubs/burning-bush/burning-bush-care.htm