Why does my brand new phone overheat when using TikTok?

Around November I bought a brand new iPhone 13, and I had no issues with it (except for transferring the data but it was fixed), but recently (I had went overseas where TikTok was banned) I came back and started using the TikTok app it has made my phone overheat and battery drop very fast. Usually I use about 10% per hour, but when I watch TikTok my battery drops very fast. This has never happened before I went overseas, is there a fix for this? Or do I have to bring my phone in to Apple?