As noted in prior discussion, some coffee makers continue to draw power (ranging from about 1 watt to almost 60 watts) even when turned off. When this was raised, I decided to check my three Keurig models with my Kill-a-Watt meter. ALL THREE drew power when turned off, and the VUE model drew 57 watts.
So, if you have a Kill-a-Watt or similar meter, you can check yours. Smart plugs also work, but can be a pain to clear after you’ve contaminated their data this way. Otherwise, unplug your coffee maker(s) for a while and see if that helps identify this annoying trace.
Note also that lots of modern appliances draw power, whether or not they are turned on. TV’s are one common draw, but many other appliances do too. Some pulse as you describe, some just dray a small amount for their electronic controls. Our new “Instant Pot” draws a few watts continually, for example. So does one toaster oven.