It’s very easy to find examples of stock prices jumping after major layoffs going back may years, e.g. https://www.spokesman.com/stories/1996/jan/03/att-rings-in-y...

That article even says “ Wall Street, in keeping with its cheerful attitude about layoffs, […] investors bet that profit-sweetening job cuts, though perhaps not as dramatic as AT&T’s, would remain in vogue among large corporations.

Large layoffs have always been looked upon favorably by investors.