Haha, they are rich but they acquired this small company. I don't know what they were thinking while building backend in PHP, from the looks of it, majority of their devs are proficient in that only.
IMO the question is not whether you should take a PHP job, it's whether you should take a job building a hosting control panel. Is that type of work something you're interested in? Do you want to become an expert in web hosting? There are lots of companies in the web hosting space, so it could be a solid career domain, but not if it's super boring to you.
I mean if I take up this job my next job would not be in the same domain. I don't have much interest in webdev, but this role also provides the infra exposure so I thought of interviewing.
Also wouldn't using Java or Golang make more sense here if the scale is such?