One other thought… were you connecting to 5G or mm-wave networks previously? You said you had a legacy in the other thread.

5G *can be* very energy-intensive, I’m not sure what factors contribute. I find my 13 mini loses almost double the battery using 5G over LTE (I’m outside the US), so I’ve set my usage to LTE max (or 3G/2G), not 5G On or 5G Auto.

Or, perhaps it’s just time to replace the battery; it’s nearing 4 years now since the 13 released. I’m in the 70% range myself.