After the previous "bug" in X.com where users didn't see their following as frequently in For You, now X quietly introduced a new dropdown for Following that is no longer chronologic by default but "Popular" whatever that means. This has essentially made posts go into the void and larger accounts get even more engagement. For all we know the algorithm promotes them if they pay more for boost instead of showing people you actually Follow by Recent.
X.com Following sorted "Popular" by default | Heykuki News