I accidentally laid a polyester mat on the heated floor tiles outside my shower and it got really hot in that spot-like burn your feet hot-and now the whole floor heat system in the bathroom seems like it won't heat past 73 degrees.
I actually JUST had this installed so I don't have a really good baseline for how it worked before, but I can say that the thermostat was set to 75 when the incident happened, and now it seems like it's constantly trying to heat but never goes past 73.