No fed law explicitly restricts where distilling above a certain percentage may occur and bans it at home. The government position is that allowing home distillery would make it much harder to catch people selling untaxed spirits. The 5th circuit says that logic would allow the government to ban the home making of anything they wish to tax and is thus overreach. The 6th circuit basically says the feds have always taxed alcohol and prior to the home bans tax evasion was rampant thus it is not overreach to ban this specific activity.
Some guy on YouTube who does medical videos claim the ban is in place to protect people from drinking methanol-contaminated liquor. I don’t think that’s the real reason at all, as it’s really about Uncle Sam wanting their share of the financial windfall.