Clash windows binary is built with latest version of go, which could specifies 4 tiers of instruction set used in compiled binary. Need to check if any logic in the binary used AVX2 instructions in tier3.
Linux -- objdump
Windows -- dumpbin, dumpbin.exe comes with visual studio
Open Visual studio command prompt (or powershell) from visual studio tools bar - Tools - command line - developer command prompt
dumpbin.exe /disasm clash.exe > decompiled.asm
I used sublime text to find the instruction strings, like vpand. It seems like all AVX2 instructions starts with v