There are several different causes for root galls. Nematodes is one. I suspect a plant virus is another. Do not recycle any soil from this tree into pots for other trees. You might transmit the nematodes, if they are present. The are nearly microscopic, difficult if not impossible to see with the naked eye.
Position this tree so that water run off from rain or irrigation does not drip into or onto any other tree in your collection. You also want to keep leaves from this tree from falling into pots of other trees.
What ever is wrong with the tree, it might not kill it. It might not be contagious, but it is best to do a Covid19 isolation for this tree.