How much has changed in terms of resource packs from 1.21.4 to 1.21.8?

Hello! I've recently started working on a "soft reboot" of a server that I'd been running for my friends. It had a resource pack for some custom items, which as far as I remember were all added through item model definitions.
I'm updating the server from 1.21.4 to 1.21.8 - will I have to change a lot in the resource pack in order for it to still work properly, or should the old pack be fine? I've been out of the loop for a couple months.