Without actually seeing these boards, seems many are going back to relays (click click) from triacs which do not handle transients particularly well.  Inductive loads (motors, valves, solenoids) can kick back peak voltages in excess of the RMS supply voltage.  Even heaters and lamps can be troublesome, because their cold (turn-on) resistance is very low.  My thru-wall aircon (PTAC) has relays on all loads, even double-sequential relays on 240V.

This goes somewhat against the trend of deliberately designing control boards such that they are prone to failure, and charging WELL in excess of their value for out-warranty replacements.  One wonders if the spreadsheet jockeys have done a turnaround and determined that reputation DOES matter.  As in, if your Whirltag eats 5 boards in 2 years, your inclination as a customer is likely away from buying another Whirltag.