I’ve been using Daikin heat pump at my 1600 sq ft house + unfinished basement since 2017 with zero issues. It’s actually cheaper than the boiler with radiant heat I had before since natural gas is so pricey these days. Cheaper than Mitsubishi but not the cheapest by any means. I think Mr. Cool is a pretty popular low end heat pump, could’ve been that maybe?

Or maybe that particular landlord simply got too small of a unit and/or hired a crappy installer who cut corners?