Is the lack of bleeding with Slinda tablets a cause for concern?

Slinda are single-component contraceptive pills that are characterized by the fact that when they are used in many women there is no withdrawal bleeding. According to the Slinda tablet manufacturer, "Withdrawal bleeding (defined as bleeding that begins within 4 days with placebo tablets and lasts up to 8 consecutive days) was most common in the first cycles – withdrawal bleeding occurred in less than 40% of women using single-component tablets and this frequency decreased over the course of the study. After 9 months of taking the tablets, withdrawal bleeding was reported in less than 20% of women using the tablets. " I attach a link to the article about single-component tablets: https://www.gdziepolek.pl/kategorie/tabletki-antykoncepcyjne-jednoskladnikowe I also attach a thread in which patients shared their opinions about the drug Slinda: https://www.gdziepolek.pl/opinie-i-pytania/22556/slinda-jakie-sa-opinie-o-leku-slinda