Code that has been tested and hardened for years? Code that is now being audited and patched quickly with the help of LLMs? Why would I worry more about such a code base than something new and not time tested?
New code bases tend to be less secure than old ones regardless of language.
PHP having a security vulnerability related to uploads isn't too shocking and it isn't a sign that C is unsuitable for language implementation. Are you willing to say the same of every other language implemented in C? Are you willing to toss out your OS?
While a safer tool is often a better tool, there are occasions in which the more hazardous tool is the correct tool for the job. If a person is cutting some flooring he/she will probably want to use a miter saw, but for some cuts, a jigsaw is more appropriate. For some applications, Ada, Rust, or Python may be appropriate, but in some situations, a developer needs to reach for ASM or C.