down the tubes

Popular UK expression, especially 20 or thirty years ago = when your life or a situation is fast deteriorating or going rapidly downhill

Tubes = probably has its origins in toilet tubes or pipes

We were good at first but our relationship is going down the tubes

Our season has gone totally down the tubes and looks like we'll be relegated

down the tube

Another way of saying that something is really going to pot -- when you say such-and-such is going down the tube, it is spiraling downhill extremely rapidly.

Man this drone flight is really going down the tube...O FUCK, There's a tree!!! (*CRASH!!!*)

That woman's performance on American Idol started to go down the tube when she forgot a critical lyric to the song she was performing.

Down the Fauci tube

Going Down the rabbit hole, off on some unknown tangent

Nicolle Wallace has gone down the Fauci tube, away from her job description