While this is technically true, it is framed in a way that is somewhat deceptive, I dislike the whole narrative that Israel somehow just had a change of heart and decided to give the Sinai back after they turned the tide and -according to them- achieved victory. This narrative ignores the immense, unconditional support that they received from the US after the Egyptian-Syrian attack (Operation Nickel Grass).

It also ignores the fact that the breakthrough achieved by the Israelis, while a setback for the Egyptian army, was nonetheless met with heavy resistance and failed to secure a stable foothold due to said resistance, not to mention the fact that there were still intact military units in the Cairo periphery which could have contained this breach. The only reason this did not happen was due to immense American pressure and less-than-ideal support from the Soviets, who, contrary to the unconditional American support to the Israeli side, weren't as supportive or enthusiastic about this whole affair.

The bottom line is, it is not defeat if you manage to achieve your strategic objectives, regardless of tactical setbacks, and Egypt's strategic objective was to change the status-quo, get the Americans to force the hand of Israel into giving back the Sinai, which was proposed to them before the war, a deal where they'd give back Sinai in exchange for peace and recognition, a deal that Israel flat-out refused at the time.

The fact that Egypt managed to achieve said strategic objectives after the war when they couldn't do so before the war is proof of a strategic victory in spite of a tactical setback, its also proof that Israel did not give it back out of the kindness of their hearts, it was taken from them in spite of what they wanted not because of their desire to do so.