In a Reddit thread talking about John Gruber's iPhone SE review:

I disagree with him about the battery part. My wife has a second gen SE and battery doesn’t make it through a work day. Even if the A15 is more power efficient, the display still sucks the most power and is unchanged, and 5G could impact the battery too.

The bottom line is the battery in the SE is too anemic for modern phones. If the battery can’t last, then the SE isn’t the “comfort” iPhone, it’s just the “familiar” iPhone.

We don't know how big the battery is in the new SE, but this is a complaint I have heard from several 2020 SE owners. There could be reasonable debate around how important things like large screens and Face ID to SE buyers, but it's pretty hard to argue that these folks don't want good battery life (especially battery life that stays good 2-4 years later when the battery health is much worse).

The 2020 SE had a 1,821 mAh battery, and even if the new SE is a little bigger, we're still likely in the 1,900 mAh range (although my money is on it being the same size). For comparison, the iPhone 13 mini has 2,438 mAh, and the "standard" iPhone 13 has a 3,240 mAh battery, for comparison. Those are driving bigger screens, yes, but standby time and battery health degradation over time are still factors and it's a shame that this legacy design also forces a really small battery by modern standards.