Help please

PTgal💜 • Fri, Dec 05 • Married 6 years, just had my rainbow, a baby girl, in April. Have pcos, endometriosis, low thyroid, and have had 4 mc.

Not sure what the dip means on my bbt chart. My temp is still above the cover line but not sure why it lowered. Is this normal, could it be an implantation dip, or something else? I'm only on day 22 and My cycles are 30-34 days in the last 6-8 months. TYIA :)