I don't know about Twilio specifically but Covid is the biggest reason for most of the current layoff rounds.

Kind of the opposite of the beginning of the pandemic, when companies with in-person employees were laying off staff and moving to work-from-home and online companies like Zoom, Shopify, Teledoc, Twilio began booming. But now many of those brand new customers are returning to their old ways.

These internet companies "over hired" in the sense that they got a massive unexpected influx new demand they needed to scale out for, and no clue how long this would last. Will it fade out next month or be a decade long pandemic?

Many companies also expected higher customer retention after covid than they're actually keeping. If you look at trendlines for online shopping, work from home, etc related industries covid caused an instant jump in their growth equivalent to about 5 years on the trend line. Rather than staying "in the future", demand is declining back towards a trend line that otherwise ignores covid.

Investors in high-growth companies like to see rapidly expanding headcounts.

And when you're growing fast there's a real impetus to fill seats FAST and there's not much discipline around making sure you're hiring well. So you end up having to collect more people than you need because not all of them are well suited to their roles and you've got a lot of new projects that everyone isn't fully spun up on so there's always a surprising proportion of people who are being spun up or wound down on random projects all the time without directly committing any code. Companies that grow like this tend to end up with a lot of dead weight and bad business processes that spontaneously appear to shift that dead weight around to where they don't drag things down.