What fees does BNB cover on Binance?

I have literally looked all over the internet for this and I can’t find anything which is why I’m asking. I feel like someone would have asked this before.

I thought BNB covers all fees and when I transferred 5k from my bank into Binance, the fee was 25$ but it didn’t use the 25% off using BNB… why? I thought BNB covered all fees.

I specifically put money into BNB so it would cut my 25$ fee from my bank to Avax on Binance