TL;DR just tag it correctly, okay?

This is an ever occurring issue developers seem to forget about as mod loaders and in turn end users settle for a specific version of the game to be considered LTS (long-term support). 1.21**.1** being one of those cases.
Due to a hotfix short after 1.21.0, the NeoForge team quickly abandoned the outdated initial release of Minecraft 1.21 and since then provides active support for 1.21.1 instead.
Third-party launchers such as Prism do not recognize any non-1.21.1 marked mods for its integrated search function for either CurseForge or Modrinth. This obviously results in Tropicraft or any other non-compliant mod to be invisible to end users, resulting in a lack discoverability and less coverage for you.

Please fix this in the best interest of both parties. 1.21.0 mods function just fine on 1.21.1 if this is a concern to you. In the event they don't, dealing with it still remains in both parties' best interest as I highly doubt you'll want to stay on an abandoned version of the game, unsupported by the relevant mod loader(s) as they moved on to the hotfix.

As a modder, 1.21 and 1.21.1 should work since 1.21.1 was some patches for light suppression and more.