It's an interesting thing and we can only speculate from the outside, but there's some obvious reasons why they'd literally hand out money in the form of free compute to people who have already committed to paying them.

- They've had to commit to minimum spend with their suppliers and their actual usage is below that level, so they might as well give it to end-users. That implies either their demand is waning or their forecasts were off.

- They want the usage numbers for this period to be higher and are willing to spend money to achieve it. I guess if they're about to IPO maybe showing more usage is good?

- They've got a lot of competition and want to keep market share. With lots of new models coming out, some of them much cheaper than Anthropic's options, you can see why this might make sense but it's effectively burning cash, so they won't want to keep doing that for long I'd guess...