The specific rules are implemented in local laws, so it probably varies a bit from country to country, but generally it’s illegal to market something as a special offer unless it actually is cheaper than before. The sign says “save more”, which would be misleading marketing.

There are other ways to work around it though. For instance by alternating between two similar products biweekly, or simply by not having that specific product before Black Friday, making it appear like a special offer even if it’s sold at full price.