If you’re helping Mini 1 owners, you’ll want to pay attention to, and recommend the firmware that works best with the slicer you’re using. As far as I know, there was a cutoff where the Mini 1 went unsupported (“legacy”) but they were still compiling the firmware for it. There were some changes to Marlin that weren’t accounted for so they were providing “updated”, but untested firmware.
Posts like this one, or this one, and plenty of others on other discussion sites are pretty common these days. The mini1 is built strong enough to outlive the support, and they’re getting passed on to people who don’t have the “figure it out” motivation that owners form 10 years ago had.