no idea why this happens but is probably one of the more annoying bugs I encounter on every map. this bug will happen randomly after walking out of thick brush, and it will keep giving the audio and visual indicator that you are still walking through thick brush even though you are no longer walking through thick brush.
I've had this happen while walking on roads or the beach after walking through thick brush. the only fixes that I know of are either keep walking and scare everything away and wait for it to fix itself, stand still till it fixes itself, fast traveling to a tent or outpost, or to reset the game. this bug happens allot when using the ghillie suits so I don't wear them. I have included 2 videos of the same location while I was in Parque Fernando one shows the audio bug happening and the other is the same location but with no bug (after waiting in place for like 5min and the bug fixing itself).