There is currently no evidence that lavender has any effect on the effects of birth control pills. In the case of citrus fruits, their consumption should not affect the effectiveness of contraception, unless you observe alarming symptoms after eating them, e.g. digestive problems, vomiting or diarrhea, the occurrence of which up to 4 hours after taking the pill may contribute to a decrease in contraceptive protection. The safest thing to do is to keep an interval of about 4 hours between taking a pill and consuming lavender lemonade.

I encourage you to read, the following article will be useful to you:

https://www.gdziepolek.pl/artykuly/czy-jedzenie-i-picie-obnizaja-skutecznosc-antykoncepcji

If necessary and in any further doubts, I encourage you to consult a doctor, the Gdziepolek.pl portal allows you to take advantage of teleconsultations:

https://www.gdziepolek.pl/telekonsultacja