Wagos my man, wagos. Its wire nuts from the future.

Kill the breaker undo whatever the monstrosity is. Each hot, neutral, and ground gets its own Wago. You buy the type that has enough holes for your problem. If theres 3 hot legs that all should all go together after you remove the fixtue get (3) 3-holes (one for 3 hots one for 3 neutrals one f0r 3 grounds). Strip the hot wires so theres no bare copper outside the Wago and clip em all in the Wago, do the neutrals and grounds in their own wagos and your done. No fire haze. Safer than wire nuts and easier. And I'm not a salesman just used em before.

Wagos!

probably you need 12awg size (the thickness of the copper cable)

Hardware store or amazon. Seriously easy. Cheap. No need for a box. Works just as well for weird 4 wire 277v or whatever.

.....just dont put hot and neutral together. Hots with hots neutrals with neutrals.....