In the last few weeks, the mempool size has grown significantly. You can see with a mempool fee viewer such as this one that overwhelmingly, transactions are growing at the 120-140 satoshis/byte fee range.
Why would this particular level grow so much faster than any other level? Is there any activity that is more likely to be in these transactions? (like sending money to exchanges, activity from certain wallets, certain blockchain services, etc...?)