This is generally the way Mastodon displays posts, that they do not appear in an orderly manner.

In my opinion, this is not a contingent consequence, but the problem is a bit deeper: Mastodon staff knows well that helping Mastodon users to use groups better (for example by helping them to visualize them better) means helping competing projects like Friendica, Lemmy, Mbin, Piefed, gup.pe and even Peertube (which also works as a synolos between user (author) and group (channel). Helping the rest of the Fediverse means giving up the dominant leadership position that guarantees them subsidies, donations, visibility and, above all, the possibility to do whatever the fuck they want, imposing de facto standards.

Distribution of active users in the Fediverse (source: fedidb.org - 12/2024)

PS: this is why I am a supporter of Friendica, Lemmy/Piefed, Wordpress, Mbin, Peertube and Bonfire: because virtuous competition brings diversity and diversity brings resilience