FRH[exp_] corresponds to FixedPoint[ReleaseHold, exp], i.e. FRH removes all HoldForm and Hold in exp.
Hold[1 - 1 - Hold[2 - 2]]\text{Hold}[-\text{Hold}[2-2]+1-1]
FRH[%]0
Isolate[ToRadicals[Solve[x^3 - x - 1 == 0]], x, IsolateNames -> KK]\{\{x\to \;\text{KK}(21)\},\{x\to \;\text{KK}(24)\},\{x\to \;\text{KK}(25)\}\}
FRH[%]\left\{\left\{x\to \frac{1}{3} \sqrt[3]{\frac{27}{2}-\frac{3 \sqrt{69}}{2}}+\frac{\sqrt[3]{\frac{1}{2} \left(9+\sqrt{69}\right)}}{3^{2/3}}\right\},\left\{x\to -\frac{1}{6} \left(1-i \sqrt{3}\right) \sqrt[3]{\frac{27}{2}-\frac{3 \sqrt{69}}{2}}-\frac{\left(1+i \sqrt{3}\right) \sqrt[3]{\frac{1}{2} \left(9+\sqrt{69}\right)}}{2\ 3^{2/3}}\right\},\left\{x\to -\frac{1}{6} \left(1+i \sqrt{3}\right) \sqrt[3]{\frac{27}{2}-\frac{3 \sqrt{69}}{2}}-\frac{\left(1-i \sqrt{3}\right) \sqrt[3]{\frac{1}{2} \left(9+\sqrt{69}\right)}}{2\ 3^{2/3}}\right\}\right\}