That symbol is called a “fall” and (like with the scoop discussed earlier this week here:Sliding across strings - #10 by JoshFossgreen)
On bass, it’s another way to add sauce/grease/style/flair.
It’s a non-definite slide off a note so that you get the sound of movement, but nothing dramatic or specific. No actual destination, just the vibe and sound of sliding down, away, out of the note.