If you narrowed the scope to within 50 years, you wouldn't be able to find one at all.
This is because modern mathematical theory research has developed to its extreme, and with the aid of computer computing power, it is now extremely difficult to achieve groundbreaking mathematical breakthroughs, and many mathematicians cannot even find the most basic research direction to work in.
Zhao Yi's math research can be considered at its peak, with two significant achievements: the Goldbach Conjecture and the three-dimensional tremor waveforms. In comparison, the weaker Twin Prime Conjecture proof progress, Collatz Conjecture, etc., can only be regarded as secondary achievements.
Once mathematics research reaches its peak, it becomes very difficult to produce more results.
Math is the most difficult subject to achieve results in.