Commentary for Exodus 31:8

הטהרה THE (PURE [CANDELABRUM] — It is called טהרה because the term זהב טהר, pure gold, is used of it (cf. Exodus 25:31) (not טהרה in contrast to טמאה).

So called on account of its pure gold. Rashi is answering the question: Does this not imply that the other vessels were not pure? Alternatively, Rashi is explaining that טהור means “refined,” not “ritually pure.” (Re”m)

ואת המנורה הטהורה, “and the candlestick, the pure one;” none of the other furnishings of the Tabernacle have had the adjective; “the pure one” added to it, except the candlestick and the table in Leviticus 24,6. The reason is that neither the table nor the candlestick ever had blood sprinkled on them.