Meconium or echogenic

My 20 weeks anatomy scan was totally normal down syndrome was normal nothing to be worried about 28 weeks ultrasound they saw a bowel movement which my dr said could be meconium stained so she wasn’t sure about it but she also told me it could be echogenic ..

So today at my 29 weeks ultrasound they saw something and didn’t tell me until my dr share the report but I was just wondering and scared what it could be and what does it mean to my baby ?

Is it safe for her to stay in meconium ?

If anatomy scan was normal then is it possible to show baby having Down syndrome later in ultrasound

Someone please help I am so worried