It's been true since November 30, 2022. Each year since the end of 2022, progress has been significantly faster than in the previous year. Completion speeds up everything else. And it will be true for many years to come.
There is no slowdown. The most important people who are working at the frontier, like Noam Brown, expect progress to speed up next year. The difference between December 2024 and December 2025 will be way larger than the difference between December 2023 and December 2024