Actually due to Bitcoin price increase then we feel his fee goes up,
1 week ago when Bitcoin price is still $ 5300 in Coinbase fee to exchange Eth To Btc about $ 2,5 then yesterday I exchange again from Eth to Btc fee about $ 5,
from I take the conclusion, the fee rises because the price of Bitcoin rises ..
I also think in that way the coinbase increased the transaction fee due to the increase in the price of bitcoin.But some guys explaining that the price increase is due to the size of the transaction increased but i don't know how the size of transaction will increase because I sent the same amount of bitcoins twice.
Here in actual the fee system is different from the normal fee system in banking sector . Here the amount of the fee for that bitcoin that you will transfer will not depend upon the price of the coin or simple Wallet system .
Here it depends upon the input and output of the transaction .
If you want to send that bitcoin( recieved from single person ) to a single person then you will be charged less , but the same amount of bitcoin that you recieved many people and want to send another person then surely the fee will be high for you ( Because you received from many persons ) .
Hope you understand the technology of the fee system in the blockchain.