I think to some extent all ISAs that are asked to do performant computing inevitably drift from RISC/CISC into FISC (Fast Instruction Set Computing) in the sens

I think to some extent all ISAs that are asked to do performant computing inevitably drift from RISC/CISC into FISC (Fast Instruction Set Computing) in the sense they get instructions that are specifically designed to accelerate the most common workloads they'll be executing most commonly. In ARM64's case this is things like the infamous "javascript" instructions that emulate x86 floating point (which is also part of how javascript works for speed reasons). In x86 this has lead to a subset of instructions being super fast while anything off that beaten path is now slow (avoid the LOOP instruction at all costs!) as well as specific extensions being added for common work loads (AES, Crypto, FMA etc.).