Let $d$ be the least positive integer such that there are infinitely many distinct prime pairs $\{p,q\}$ with $|q-p|\le d$. The twin prime conjecture is equivalent to $d=2$. In 2013 Yitang Zhang proved that $d\le 7\times10^7$. Maynard improved this to $d\le600$, and a Polymath Team led by Tao obtained further that $d\le 246$.
Quite recently, Chunlei Liu released a prperint On the gap between primes in which he modified Maynard's approach to get $d\le 130$.
Question. What's the advantage in Liu's modification of Maynard's method? Can Liu's work be improved further? Can one prove $d<130$ via suitable refinements?
I have not read Liu's paper very carefully. Your helpful comments are welcome!