iPhone 14 Pro Max charging slow.

Hi, I bought an iPhone 14 Pro Max last month. The phone is great and can last me 3/4 days but my issue is the charging. It is taking sooo many hours to charge. So last time I charged the phone it took over 6 hours to charge to 100%. I thought maybe I was charging it through the extension wire so it might not be transmitting enough power. My phone died today at 10:59am, I put it on charge at 11am through the wall socket so determine if it was the power output that was taking it’s time. I’ve just turned my phone on to see the progress and it’s only charged 42% for 1 hour and 45 minutes, I’ve seen through multiple videos on YouTube and through articles that this isn’t normal. I am using a genuine apple 20w charger, usually put my phone on charge when it dies and leave it turned off till fully charged. If anyone has any insight I’d love to hear from you, thank you for your time taken to read this.