The help information for the Moving Average tool can be found at https://help.libreoffice.org/7.0/en-US/text/scalc/01/statistics_movingavg.html?DbPAR=CALC#bm_id04001.
A new option was recently included on the associated dialog, entitled "Trim input range to actual data content". This needs to be added to the help page.
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Contents suggestion and patch is following immediately
Trim input range to actual data content
Check this box to allow trimming of the input range to the actual data content before computing moving-average. Trimming data ignores unused or empty cells after the last non-empty cell on the bottom right of the input range, thus reducing the computing load of the moving average to the actual data. This checkbox is enabled by default.
Olivier Hallot committed a patch related to this issue.
It has been pushed to "master":
tdf#132465 "Trim input range..." option on Calc's Moving Average dialog