new iphone battery does not last long

The measure of battery health deterioration/drainage is subjective and can vary depending on individual usage patterns. There is no universal standard to determine whether the battery health deterioration/drainage is normal or abnormal because it heavily relies on how the battery is used and maintained.

Protect & Prolong the Life of your iPhone's Battery:

1. About the battery usage on your iPhone, iPad, and iPod touch ...
2. Batteries - Maximising Performance - Apple (IN)
3. iPhone Battery and Performance

I've seen a few posts recently that Instagram was playing a role in draining battery more than normal.

https://discussions.apple.com/thread/254804894

It might be the 3 hours you spent on Instagram.

Where did you have the battery replaced?