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a downward anomaly like today is an upward one.
Weight can fluctuate a couple of kilos or more day on day, for any number of reasons. To the extent that day on day is almost meaningless.
Even if your week on week average is 1kg being dropped, that's well within expected variance. A low start of week measure against a high end of week, and it you can have a heavier weigh in. Even week on week needs to be viewed critically.
You can end the week heavier on a calorie defict, and still be losing weight longer term.
I think recommended best practise is to do a daily weigh in. You see the general trend rather than being misled by fluctuations.