Mucous plug or discharge?

Nina • 7.26.18💍 Happily married to my soulmate❤️ #1 June 2019 💕🌈 #2 April 2021💕

Been losing this for a few days. Was at L&D Friday for some preterm labor symptoms and they said I was 2 cm but not showing contractions on the monitor. First it was just clear/yellow now it’s starting to be brown.. what is this?