Yes same, here in the UK the 12 mini has been on sale on Amazon UK for £599 for the last few months (£100 off RRP), so will wait for the 13 mini deals like this and then snag one probably in the Midnight colour. For me the larger battery and 128 GB base storage are the best upgrades overall. The camera upgrade and higher brightness are bonuses.
Here the 12 Mini was available with 200-250€ off in some sales. You just need to be patient. I myself don't need the 200€ but why not safe it and invest it in something else like the new AirPods 3 when they come out if I don't need the 13 Mini right now.
I also think about what I do with AC+. Do I buy a second 13 Mini in time for a steal just to be sure, which would be a big amount compared to going AC+ for two years just to be safe, maybe even with the newly introduced theft bonus introduced here now, which would make it more expensive again (229€ for two years). ATM I don't have AC+ for the first time because I didn't need it. But the 13 Mini is a different story. Or do I make monthly AC+ payment which could go on forever, no two year limit, but this would be even more expensive with 8.50€ a month without theft insurance...
My battery has gotten down to 99% finally, iPhone bought in February, with the iOS15 B8 upgrade. But I almost exclusively charge it with the 5W charger, never magsafe or wireless charging, because I don't need it. Sometimes 12W charger. Never my 20W charger. It is more convenient but I don't need it. If my 12 Mini would have low battery all the time because of intensive use I would use the 20W charger too. If I don't have the time and would be out all the time I would use it too. But I often have the time to let it charge with 5W.
I also think it has something do to with how hot the battery gets during charging and also during use. Do you use your Mini for extensive tasks and games, magsafe charging, use it while charging etc. Maybe you live in an area where it is hot all year. All that stuff. Plus luck. Some batteries have better quality or at least higher capacity than they should, some only the capacity Apple mentions.
My SE 1 which wasn't used all that much but quite some time is still at 97%. My 11 which I had for a year as my main device and then gave to my parents last year, with very moderate use from then on, is at 96%.
My Macbook 12 has gotten down in capacity quite fast imo. And I use it while charging, it is getting hot when using certain apps etc.