For everyone who's post nasal drip started after Covid infection, maybe this is interesting. Mine started thin, then changed to thick and sticky including crusts as of today (18 months now). ENT has no clue, Staphylococcus A. was found and after antibiotics and xylitol nasal rinse the post nasal drip disappeared for a month and then returned. Next to the drip I have several other nasopharynx related symptoms and because I can't stop doing my own research when I have a real bad day (😂), I came across chronic nasopharyngitis, also known as epipharyngitis. My symptoms are a 100% match, never had that before with other potential conditions, so I'm gonna discuss this with my ENT. Maybe worth to discuss as well if you suffer from the same symptoms.