Possible girdling root on Keraji

[NativeNC]

I figured maybe I was having iron issues, but after looking I have found what appears to be a girdling root at the base of the tree, any advice or tips? Leave it, excavated and remove?

[sheaper]

I think i see what youre talking about but not sure how to go about "fixing" it.  have you taken any soil samples for testing ? are nearby trees thriving?

[NativeNC]

I had a sample through NC State done a year or so ago, the ph is slightly acidic, maybe a 5.5 or so. Other than that, nothing stood out to me. Did my best brushing away around the growth pictured above, to see if I could locate any girdling. I did not immediately see signs. The nearby citrus trees are all not displaying any similar issues. Alongside this, I will add that I've debated if it was planted too low. This mandarin is one of my original 4 citrus I planted Spring of 24, so at that time, I was not as keen to planting on a mound, as I have since learned after planting an additional 10 citrus trees. I will upload a canopy/leaf image shortly to add to the dialogue