Actually “Jehovah” or “Yehovah” was a mistranslation/transliteration of YHWH combined with the vowel markings of “Adonai” (lord) added to remind readers to avoid pronouncing The Name and to substitute Adonai/lord.

Written Hebrew had no real vowels — vowel markings were added around the second century CE.

The forward of most Bibles explain this in discussions of the Tetragrammaton as do any good collegiate dictionaries (under “Jehovah”).