Regular expressions in Power Automate are problematic. Also, while it can crop the text before the first occurrence of a space, it cannot crop the text after a last occurrence.
However, you can reverse the text, crop everything before the first space, then reverse that to get everything after the last space:
flow to crop text after last space
LOOP FOREACH CurrentItem IN FileContents
Text.CropText.CropTextBeforeFlag Text: CurrentItem ToFlag: $'''%' '%''' IgnoreCase: False CroppedText=> CroppedText IsFlagFound=> IsFlagFound
IF IsFlagFound = $'''true''' THEN
IF CroppedText = $'''%'DAAR'%''' THEN
Text.Reverse Text: CurrentItem ReversedText=> ReversedItem
Text.CropText.CropTextBeforeFlag Text: ReversedItem ToFlag: $'''%' '%''' IgnoreCase: False CroppedText=> CroppedReversedText IsFlagFound=> IsFlagFound
IF IsFlagFound = $'''true''' THEN
Text.Reverse Text: CroppedReversedText ReversedText=> CroppedText
Display.ShowMessageDialog.ShowMessage Title: $'''Cropped Text''' Message: CroppedText Icon: Display.Icon.None Buttons: Display.Buttons.OK DefaultButton: Display.DefaultButton.Button1 IsTopMost: False ButtonPressed=> ButtonPressed
END
END
END
END
Note you will have to get the file or list into FileContents first, and you might want to output CroppedText to a file instead of displaying it.