Money & WorkFact
The crossed-out price must be the lowest of the last 30 days.
Since 28 May 2022, Germany's price indication rules require that any advertised price reduction be measured against the lowest total price charged in the preceding 30 days. That kills the old trick of raising the price shortly before the sale starts.
Useful: If nothing next to the crossed-out price mentions those 30 days, the "discount" is often no discount at all.
Source: e-recht24.de