my 2018 model, with a 256 gig SSD, 8 gig of Ram, and a Core i5 processor. I actually thought I might be taking a step backwards, as the late 2012 model has a Core i7 processor.
Right, and good to see someone confirm it. Today's Intel-i5's are faster than a circa-2012 i7. I've even seen a desktop i3 that is faster than a circa-2010 Intel-i7.
If I buy a MacMini-2018, I think it will be similar to yours with the Intel-i5. With the small-case and power-supply ... it just seems like a more reasonable config.
Good to see the posts of happy MacMini-2018 owners. It helps to offset all the trouble-threads. Still not sure if some machines are just bad, or others are getting revised-motherboard models. However, it seems clear that you must be running the latest Catalina, because that is the only way you get any new/updated firmware for sub-processors and micro-controllers (in addition to latest macOS and drivers).