It's equally possible that they added DT_HASH lookup to achieve glibc 2.34 compatibility. The old way for getting the original dlsym function after interposing

It's equally possible that they added DT_HASH lookup to achieve glibc 2.34 compatibility. The old way for getting the original dlsym function after interposing dlsym stopped working because the (internal, usually uninterposed, now unused) __libc_dlsym@@GLIBC_PRIVATE symbol went away in glibc 2.34. But a program can still obtain the dlsym function address by looking at the ELF data structures directly. This would explain why people are so annoyed: there's unplanned extra low-level work to enable glibc upgrades two years in a row.