It may be different in other regions, but where I live (Vienna), mains voltage has changed. During the 80ies it was 220 V (nominal), now it is 230 V (nominal). It is a "real" change, not the standards only. You could/can measure it with an AC volt meter.
After the change (close to the millennium), there were problems with "sensitive devices". I do remember problems we had with some elder tape recorders (I was working at a radio station).