Is Prism Launcher allowed in speedrunning? And is Fabric also allowed? i only have fabric mod because my laptop is not really fast (It's a 2011 laptop so ofc it will be slow). whoever answers out there, thank you in advance.

Edit: is Linux Platform also allowed? and how to set livesplit in linux?

Yes, Fabric is allow (with the list of allowed mods here: https://mods.tildejustin.dev/ ; remember not to use fabric api). For Prism Launcher, idk but stick to the official launcher or MultiMC if you can.

check the rules for that stuff, but pretty sure a tlauncher is never allowed here

Yes prism is allowed. Nobody uses livesplit anymore cause there is an allowed timer mod (speedrun igt). For setting up Linux https://sathya-pramodh.github.io/linux-mcsr/index.html