We define price validities as our prices change on certain dates. So a price of 15,90 EUR might be valid from 1.1.2023 to 14.11.2023 and 16,90 EUR from 15.11.2023. This means that the price of 15,90 should be shown in the frontend today (on November 14th) and the price of 16,90 tomorrow. The price feed comes from an external system where price validities for price types are defined.