It is a breakthrough. For reference the best logic process in the US is 7nm with DUV at Intel.
SMIC basically reached parity with Intel which is the leader in logic manufacture in the US.
Globalfoundries, also in the US, is still stuck at 12nm and stopped investing into further advanced process development.
Only Samsung and TSMC use EUV machines and can manufacture at 5nm or better. Those factories which use EUV are in Taiwan and South Korea. I hear claims that SMIC is two generations behind. But that is also bullshit. SMIC is like a generation and a half behind TSMC. TSMC is at like 4nm which is a half node after 5nm. And if you look at the latest US chip designs, most are still using TSMC 5nm, be it AMD Zen 4, or Apple A16. Intel claims they will start using EUV and catch up with TSMC, but they have failed at process development over the last half decade, so who knows if they will deliver anytime soon.
Also, claims that China is behind the US in chip design are also, I think, basically BS. As can be seen by Huawei's HiSilicon subsidiary designing their own high end ARM cores and GPU, and Alibaba designing their own advanced CPU cores. For example the most advanced RISC-V chip you can actually buy in the market right now in volume is the Alibaba T-Head TH1520 in the Lichee Pi 4A. It uses T-Head's own C910 RISC-V core. And it even comes with its own vendor specific instructions.