In English, I hate both "from where" and the rarer "from whence". I first found out about the words "whence", "whither", "thence" and "thither" (respectively meaning "from where, "towards where", "from there" and "towards there") while reading the Lord of the Rings in English. I found these were powerful words that could make many sentences shorter and clearer and that it was a shame they went out of popular use...

But then, I also heard "from whence", which struck me as far worse because it was redundant and stripped the word of its power. I first thought it was a mistake, but after seing it several times I looked up how it was meant to be used to see if I wasn't in the wrong and saw that while it had started as a mistake, it came into use several hundred years ago and was used by many famous classic authors, making it acceptable.

Imo, that's probably what killed these words. I guess it had the merit of being less easily misheard, but when "from whence" and "from where" mean the exact same thing, why bother remembering "whence"?

In my native language, French, I kinda dislike "C'est quoi ?" (Litt. "It's what ?", pronounced [sekwa] meaning "What is it ?). It's a vernacular expression often found incorrect... But I also kinda understand why it exists. The most correct way to ask "what is it" is "Qu'est-ce ?" ([kɛsə] or [kɛs]). It works well when written, but I guess being too short, it can be easily misheard. For example, "caisse" (a large box) is pronounced the exact same way. The other alternative, more common in oral speech is "Qu'est-ce que c'est ?" (litt. "What is it that it is ?"). It might seem too long, but it's pronounced [kɛskəse], which has the same number of syllables as "What is it". It is redundant tho, so I understand why "C'est quoi ?", which doesn't sound like anything else, rolls off the tongue and has two syllables is winning over, and will probably be the correct way in the future, but it still kinda sounds wrong to me.