php -v prints the first php on PATH. which php or command -v php shows that path. update-alternatives on Debian can point php at a different build than the FPM unit.
Also run the package query for your OS: apt-cache policy or rpm -q. If the package version and the binary disagree, the binary may be a copy outside the package manager. That copy is the one to distrust until you know who shipped it.
Write the full version line and the package version in the ticket. For Ubuntu and AlmaLinux backports those two lines are supposed to look different. A match to 8.3.36 is meaningful for an upstream build. It is the wrong expectation for Ubuntu 24.04’s fixed php8.3 package.
Delete any phpinfo script you created for the check.