The Zend Engine's function-call-interception hooks have been a challenge for observability, leading to performance issues and crashes. The new observer API in PHP 8 addresses these concerns by providing a more efficient and reliable way to instrument functions and methods. It introduces opcode specialization, allowing extensions to target specific functions of interest without notifying every extension for every function call. The observer API also supports targeting userland functions and is compatible with the new just-in-time compiler (JIT) added in PHP 8. Additionally, it eliminates the need for forwarding along hooks to neighboring extensions, making it "noisy neighbor resistant." This allows multiple tracers, profilers, and debuggers to run alongside each other without crashes. The future of observability in PHP now has a single point of reference under the `ZEND_OBSERVER` name, enabling further advancements in this area.