Our suggestion In order to comply with both the PAngV and a clean UX, a small piece of logic would be useful:

If regulationPrice == price.unitPrice → no output. (This happens very often in practice.)

This would both comply with the legal situation and meet actual customer expectations.

1. Legal situation (PAngV § 11) According to § 11 of the Price Indication Regulation (PAngV), the ‘lowest total price of the last 30 days’ only becomes mandatory if the retailer advertises a price reduction. Source (legal text): https://www.gesetze-im-internet.de/pangv_2022/BJNR492110021.html#BJNR492110021BJNG000201377

It clearly states: ‘If goods are offered to consumers with reference to a price reduction, the lowest total price charged by the trader within the last 30 days [...] must be indicated.’ ➡ Without a price reduction, there is no obligation to display the price.

1. Confirmation by legal commentary (e.g. the article you linked to) Your linked article also clearly states that this obligation only applies to reduced prices and serves precisely to prevent misleading ‘bogus discounts’: https://www.ratgeberrecht.eu/aktuell/30-tage-bestpreis/ If the current price is identical to the 30-day price, there is no price reduction and the display ‘Lowest price in the last 30 days’ would rather suggest a false discount effect.