We looked at the photos. Some of the off-color foliage looks like winter color/browning and this can be normal for some cultivars. Also, winter color can look different based on environmental conditions such as the wind, temperatures, etc.
In the left photo - the tree on the right looks like it may have some winter color but may have some root issues but we cannot say for sure.
Check and make sure the soil drains well in this area. Mulch should be no thicker than several inches and away from the base of the trunk.
We recommend that you take the wait and see approach. Wait for spring and look for new growth and any additional symptoms. You can send us more photos at that time and we can see what you may be dealing with.