Supposing you are using like electrum wallet, you will be able to pump the fee using RBF (please by fee) but I do not think mycelium support such.
It depends because in order to use RBF, the option must be chosen before the transaction is signed and broadcasted. You can not use RBF if you did not create this type of transaction.
I took the transaction randomly from blockchair.com, it is marked as No with "Replace-by-fee (RBF) enabled?" so the one who makes that transaction can not bump it with higher fee.
https://blockchair.com/bitcoin/transaction/d66e374fb4f9a9565e38c505a1cd2c780112946e25bad7cf5fe1b981a8662696https://readthedocs.org/projects/electrum/downloads/pdf/latest/• Increase the transaction fee. This is only possible for “replaceable” transactions. To create this type of transaction, you must have checked “Replaceable” on the send tab before sending the transaction. If you’re not seeing
the “Replaceable” option on the send tab go to Tools menu > Preferences > Fees tab and set “Propose ReplaceBy-Fee” to “Always”. Transactions that are replaceable have the word “Replaceable” in the date column on the
history tab. To increase the fee of a replaceable transaction right click on its entry on the history tab and choose “Increase Fee”. Set an appropriate fee and click on “OK”. A window will popup with the unsigned transaction.
Click on “Sign” and then “Broadcast”.
The mempool has just cleared up. According to Electrum fee estimator, a 4 sat/byte transaction would be positioned 2.0 Mb from tip. So, most likely, your transaction will get confirmed within the next few hours.
I checked Electrum and with Mempool option for fee estimator, the wallet recommends 6 satoshi/byte that likely fits with mempool status. With that fee rate, transaction will get confirmation within 2 blocks. I guess the rate you were supposed is at the latest dip of mempool.
One of my transactions (20 sat/byte) have been stuck for the ladt three days and it got confirmed today.
Correct. Mempool was cleared (but not all) around 13 hours ago.
IMHO, the transaction won't have any chance to get confirmed in real soon like in the next couple of days because you mentioned you did made transaction with fee of 4sats/byte which is really low compared to the recommended fee, it maybe already confirmed even if you used 12sats or above when you broadcast the transaction.If you are not in a hurry then nothing to be worried.
The used fee rate is low than recommended fee on that day but today it is enough to get confirmation within 1 hour or at worst within 24 hours.
In reality, the mempool was dipped to the rate of 4 satoshi/(v)byte a few hours ago but did not clear all waiting transactions at that fee rate. I hope OP was lucky enough to get confirmation in the dip. If not, let's wait for coming chances till tomorrow.
It's the weekend and today is
Saturday!
Mempool was cleared about more than 13 hours ago after stacked up recent days. As of writing at 19:08 PM UTC, you can move
BTC at
4 satoshi/(v)byte. If you check on
https://jochen-hoenicke.de/queue/#1,24h, you can see that the total size of waiting transactions for fee rates from 4 satoshi/(v)byte and above is at 4.18 MB. Therefore, you can get first confirmation within next 6 blocks with fees at
4 satoshis/ (v)byte.
I am expecting lower fee rate because on Sunday institutional effects usually become smaller and fee can be cheaper. I believe that you can have chances to move your bitcoin at
2 satoshi/ (v)byte tomorrow, on
Sunday!