This was 10%. Nothing new. Musk has done this periodically, and it is a bit normal in some industries to periodically layoff 10%, the dead weight.
It shows the bias of Wall Street against Tesla. As you say, a 10% reduction is nothing new, Tesla has done it a few years ago, and will do it again. Other companies periodically do it also, yet their stock goes up - example is Cisco recently. (I've owned stock in Cisco, and own stock in Tesla.)
It is a buying opportunity in Tesla stock, and it will double in price by end of year.
Drew Baglino, Tesla’s head of powertrain and electrical engineering, was among a number of top execs who quit or were laid off.