This issue was first found by someone on a server using relics (from the RelicEx mod, the server uses the latest MMC1-Fabric modpack) that gave luck. They noticed every time they reforged an item, it was always Epic.

I tested this on singleplayer by only giving me the luck effect (as the relics are hard to replicate), and noticed the issue started at around luck 40~45, but you could get other (better) tiers from time to time. Starting at luck 50 the only tier when reforging is Epic.

I know is a bit of an edge case, but one would expect that with better luck you would get better tiers and not get stuck only with Epic.

Thanks in advance!

I've tested this and it works fine for me. By vanilla the player will never see such a high effect lvl btw^^
Change the config setting called luck_reforge_modifier to a lower value to reduce the effect of luck.