Is it allowed to use optifabric (optifine+fabric) for 1.14/1.15 so i can use the lazydfu mod and duncan's auto reset mod?

no

yes it is, but not for 1.15+

*yes, but for versions 1.16 and above, no - because of nether fog. (this is also why 1.9-1.15 has separate leaderboards to 1.16+) edit: ++ other things, such as piglin trades being added, etc

optifabric is allowed for 1.14 yes, make sure you dont break optifine rules tho.

No, it's not, @Higgex

@KingLavaCactus 1.16 has separate leaderboards because of the many changes, fortresses chances are changed, and getting pearls is an entire different strat in 1.16 (and faster) The split was made before mods like sodium are used in speedrunning