Back in 2017, one of my transactions got stuck for around 6-7 days. The transaction never got confirmed and after a week, the coins were returned to the originating wallet. And recently, in January one of my transactions took almost 24 hours to get confirmed. The transaction fee is quite volatile right now. So in case you have put a low fee by mistake, then you may need to wait for a few days. The Mempool size is also getting bigger. Last time I checked, it was around 72 MB.