We have a bristlecone pine that was planted in the spring of 2022. This spring (2023) it had good overall growth throughout the plant - short as typical. A few weeks ago I noticed some of the lower branches were orange in color like they were dead. For the 3-4 foot tree there are 10-12 branches like this. I will send pictures under separate note. Hope that isn't a problem for you to connect the two messages
I suspect it is not getting enough water. These trees are drought tolerant but not until they are well established which can take a year in the case of a tree. Or perhaps it has been dry there this summer. I can't tell from the photo, but is it in full sun? That is important, too. You said the soil was well draining, which is a must. These articles should help:
https://www.gardeningknowhow.com/ornamental/trees/pine/pine-tree-drying-bottom.htm
https://www.gardeningknowhow.com/ornamental/trees/pine/bristlecone-pine-information.htm
You don't need to fertilize the first year. This article tells more:
https://www.gardeningknowhow.com/ornamental/trees/pine/caring-for-pine-trees.htm
My pines variety are pinus eldarica and pinus mogo.
It is hard to say without more information. The issues probably started a year or more ago. Has there been drought in the last couple of years? Here are some articles about pine problems that may help:
https://www.gardeningknowhow.com/ornamental/trees/pine/pine-tree-drying-bottom.htm
https://www.gardeningknowhow.com/ornamental/trees/pine/pine-tree-browning.htm
https://www.gardeningknowhow.com/ornamental/trees/pine/pine-gall-rust-disease.htm
https://www.gardeningknowhow.com/ornamental/trees/pine/diplodia-pine-tip-blight.htm
It's been dry here but water doesn't seem to help. I have aphids on other plants in the yard. Sap is weeping from places where limbs were cut off.
Usually by the time an evergreen tree shows browning, the decline started months before. So, if it has been unusually dry since last summer, the damage may just now be showing. Here are some possible reasons for the browning:
https://www.gardeningknowhow.com/ornamental/trees/pine/pine-tree-browning.htm
https://www.gardeningknowhow.com/ornamental/trees/pine/pine-tree-sap-information.htm
https://www.gardeningknowhow.com/ornamental/trees/pine/controlling-pine-needle-scale.htm