I'm afraid you're correct about it underperforming, but as an owner of an iphone 13 mini i can only say i'm very happy with it. As long as there is a mini available, i will not switch to a larger model.
The same people are saying that the mini is toast for the iPhone 14. It's gone. Maybe Tim Cook will do his Tim Cook thing and reuse the mini form factor as the next SE for the next half decade, but I wouldn't bet on it.
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[1] https://www.macrumors.com/2020/10/02/iphone-13-lineup-rumore...
[2] https://www.macrumors.com/2021/02/15/iphone-13-mini-expected...
I live in hope