Intelephense checked PHP code against its default 8.5, whatever version the project targets. Settings › Languages & Frameworks › PHP gets a PHP language level, Auto (default: composer.json config.platform.php, else the lowest version require.php allows) or 5.6–8.5, sent as environment.phpVersion; nothing is sent without a requirement. Intelephense applies the version only to documents it parses after reading its configuration, so servers that opt in (resync-on-configuration, Intelephense only) get their open documents again right after workspace/configuration is answered (new jsonrpc Handler::after_response), and Intelephense keeps one index per level because it fixes the built-in functions when it indexes. A change to a root or workspace member composer.json reconfigures the servers.
Co-authored-by: DanielADK <18214958+DanielADK@users.noreply.github.com>