Blockchain Explorer Blocks https://hedgedoc.k8s.eonerc.rwth-aachen.de/kFtMQ9aTSTis_8Gbdx6V0Q/ So, if there is a large number of transactions from the mempool so you paid out a relatively small transaction cost, your transaction can continue to be unconfirmed for an extended time period since miners/validators will choose transactions with larger fees 1st. It is quite basic https://bookmarkyourpage.com/story5664673/blockchain-explorer-mempool-the-definitive-guide-to-blockchain-explorer-litecoin-https-cutt-ly-3rj9ygbc