Q.burning bushes never turn bright red
I have older burning bushes (25 years) that look healthy, but they never turn bright red. They are more like 1/2 brown leaves and half light red in color. They are beautiful in the summer. They get lots of sunshine and lots of water and good drainage

Is it getting full sun or part sun? How many hours of sun per day? Burning bush can more easily achieve their bright red color when they are in a full sun location. In shadier locations it will be more of a pink/light red.
Have these 25 year old bushes ever turned bright red in their entire lifespan? If this is somewhat of a new development your bushes could be infested with spider mites. More information on spider mites on burning bushes can be found here:
https://www.extension.iastate.edu/news/2006/jun/070901.htm
If your burning bushes are in full sun and have never turned the bright red then it is possible that the variety of Euonymus that you have is not Euonymus alatus (burning bush). There are other varieties that have more pinkish leaves. For more information, go here:
http://web.extension.illinois.edu/dmp/palette/091101.html
For more information on the care of burning bushes, please visit the following link:
https://www.gardeningknowhow.com/ornamental/shrubs/burning-bush/burning-bush-care.htm