Let's assume that in some Western countries, due to COVID and accelerated money printing, fiat has lost 20% of its purchasing power since the start of the 2021 bull run. Cars, houses and groceries cost more by a significant amount. The current bitcoin price is not as strong, and not equivalent in purchasing power, as when it was the exact same fiat price in 2021.

In this scenario, the true bitcoin ATH would be when it goes beyond the last ATH + 20%.

Performing your own calculations with your local currency, local inflation rates, etc... what will the true Bitcoin ATH be where you live?

This is not the same as the highest fiat price for Bitcoin!

At what price point, adjusted for inflation, will we be able to confidently say that 1 BTC has never had more 'real word' purchasing power for goods and services?