I am using the latest development version of FeynCalc.
DD = I*GS[p] - g*GA[\[Mu]] . QuantumField[A, \[Mu]] - m - QuantumField[\[Sigma]] -
I*GA*SUNT[a] . QuantumField[\[Pi]f, a];
DDh = (-I)*GA . GS[p] . GA - g*GA . GA[\[Nu]] . GA . QuantumField[A, \[Nu]] - m -
QuantumField[\[Sigma]] + I*GA . SUNT[b] . QuantumField[\[Pi]f, b];
hhh = DDh . DD;
hhh2 = TR[SUNTrace[hhh]]
Originally (last century) I assumed that color traces are always done before dirac traces. It definitely it easier. Maybe the current maintainer of the code base (Vladyslav) can comment if the reverse should and could also work. I am not so sure it is needed.
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