v1 — choose this for PHP 8.2–8.4 projects, production deployments, or when you don't need the newest Bitrix24 API methods. v3 — choose this for PHP 8.4+ projects that need access to new REST API ...
PHP 8.0 introduced attributes, but the reflection API to actually read them is verbose and awkward. Want to check if a class has a specific attribute? That's four lines. Want to find every occurrence ...