Back in the PS2/Xbox/Gamecube era the SNES and Megadrive seemed to be retro while the PS1 and N64 were just “old”. So maybe 2 generations ago is the start of retro.
I think it’s definitely a lot blurrier now though. The differences between consoles and the leaps between generations are less pronounced, and there are so many y rereleases and remasters now keeping older games fresh.
A few years ago the hose on our washing machine split and we didn’t realise until water started coming out from under the units. Thankfully damage was minimal but it was a big pain to dry out.
I’ve had some of those Aqara leak sensors in place since as a precaution.
Just remember to change the batteries regularly! Easy to forget them when they are out of sight.