Seeing Etherium network fee at $8+, why?

I need to transfer $25 USDT (ERC20) to a friend. I tried doing this many times over the last few days, but the network fee was anywhere between $8 and $19 every single time, so I keep delaying.

Looking at the average network fee graph on YCharts, I can see that the current daily average is below $1.

What could be the reason that the fee I'm seeing is so consistently many times higher than the current average?