You're using something subjective that is "quality", if you ask here most people will overpraise Mitama Secureity as a great/fantastic comedy, and it's indeed really good, so why the series underperformed and the so "criticized" Yozakura sold better than everybody thought? Thing is, Jujutsu Kaisen only started to be noticed and do great after the first volume was released and became a hit, that's my point.
You say you don't have any reason to think it's because growing in popularity but you basically stated the reasons before saying that, sales were very decent, it's getting a reprint (which never happens to a flop), got a color page like two weeks ago and the rankings are slowly going up compared to being dead last before, simple, if it will really grow is one thing, but there are plenty of reasons to think that is recovering.
"Pushing" a series is basically advertising, people will not simply discover a new series out of nowhere, is just a portion of japanese readers that follow weekly magazines, most only buy tankobon so you need to "push" and advertise stuff when it shows potential of growing, that's how many things grow in popularity.