Fees for an ordinary payment were several times higher on Tuesday than on Sunday (sample report).
The reason is space: each block holds a limited number of payments, and when many people send at once, they bid for a place with higher fees. Payments with lower fees wait in the mempool until it quietens down.
If your payment is not urgent, a lower fee rate usually gets through within a day. Your wallet’s fee setting shows the choice in sats per vbyte; the amount you send does not change the fee.