@Dobby_ So
openssl-1.1.1q,1 TLSv1.3 capable SSL and crypto library
ldd /usr/local/sbin/squid| grep ssl
libssl.so.111 => /usr/lib/libssl.so.111 (0x800b6c000)

It seems that squid used openssl 1.1.1 ,the openssl will use QAT, then the squid can use QAT ?

As soon as you have access to the full, decrypted data stream it's most probably possible to cache everything.

But :
The, for example, ccs style sheet file, can have a unique name - and won't be re used ever again, so it will get reloaded anyway.
The file creation date can be set to 'now' so the browser will request a fresh copy, even if the content didn't change at all.
etc etc .