The Time range Defaults`s "Last month"、“Last quarter”、“Last year” have some bug!
"Last month" :2019-12-01 to 2019-12-31
"Last month" :2019-12-08 to 2020-01-08

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I don't think that is a bug. The current behavior is what I would expect. It's a relative time span of one month, quarter, year taken from the current date:
current date - time span (month, quarter, year,...)
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