This little amplifer makes use of an unusual output stage. It has Sziklai output pairs which are configured as a 'Non-Switching' design - meaning that none of the output transistors will completely stop conducting, even when the opposite transistor pair is delivering full output current.
The strangely placed shottky diodes at the output will help with this. Furthermore, they simplify biasing a lot. No need to place milivolts across miliohms in order to get the desired 50mA bias - the bias-setting resistor is quite high at 3.3 Ohms, which makes the circuit very robust to component variations (as evidenced by the current component mismatches ;) )

Furthermore, it has 2-pole compensation, hitting almost 70dB open-loop at 20kHz. LTSpice says that this should result in excellent distortion performance.

Use the KiCAD schematics for reference - the LTSpice schematic doesn't show all resistors, sometimes i included them as ESR into caps. It is just for showing the sim set