It doesn't appear on the charts, is not visible in the indicators, and almost nobody explains it well, but it can destroy a profitable trade without the trader understanding what happened.
The funding fee exists to balance the market between long and short positions. When the majority is betting in one direction, Binance charges a periodic fee to those on the saturated side and pays it to the opposite side. So far, everything seems logical. The problem begins when that fee becomes high and persistent.