Since I have posted the transaction ID for forum member to check, based on your assumption, do you think the mining fee could have been the reason for the untimely delay
Yes. This fee would usually be enough, but there was a spike of unconfirmed transactions, so many transactions got priorized over yours. Since the recommended fee varies a lot, there are times where, for example, a 5 sat/byte fee would be enough... until a lot of transactions of 8+ sat/byte arrive in the mempool. Making the recommended fee rise to 8-9 sat/byte. The 5 sat/byte would then need to wait until every 8 sat/byte tx gets confirmed.