The A12 Bionic and Apple Pencil support in the 2012 body, after three and a half years with no update at all.
Released March 18, 2019 · Discontinued September 14, 2021 · From $399 (64 GB, Wi-Fi)

Apple ignored the mini for three and a half years. Then it quietly gave it everything. The fifth mini kept the 2012 body and dropped in the A12 Bionic from the iPhone XS, added Apple Pencil support, a True Tone laminated display and a wider P3 color gamut. Same size and shape as a mini from 2015, and roughly three times as fast, an update nobody had expected at all, which is most of why the reception was so warm. For pilots, nurses, field engineers and anyone who reads a lot standing up, a 7.9-inch iPad that takes a Pencil is a specific and hard-to-replace tool, and this is the model that proved the category was worth keeping.
An A12 inside the 2015 mini 4 body, which reviewers accepted because nothing else in the size competed.