Question about Game Version

So i was working on a project a couple months back and it's on 1.21.4. Im planning on keep working on this version until i finish all the features i wanted and then started updating it. But i heard that a version 1.21.8 or 1.21.7 or something is a hotfix update, so now im wondering if i were to update my mods later which versions after 1.21.4 should i update it to?