Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative$$- \frac{\frac{\left(\left|{x}\right| - 1\right)^{2} \operatorname{sign}^{2}{\left(x \right)}}{- \left(\left|{x}\right| - 1\right)^{2} + 1} + 2 \left(\left|{x}\right| - 1\right) \delta\left(x\right) + \operatorname{sign}^{2}{\left(x \right)}}{\sqrt{- \left(\left|{x}\right| - 1\right)^{2} + 1}} = 0$$
Solve this equationSolutions are not found,
maybe, the function has no inflections