To have a proper website for your business, you will need hosting and a domain. Many hosting services will allow you to buy a domain and hosting. But since domain hosting (domain registration) and web hosting are two different things, you may have purchased your domain in one place and your website in another.
Having your domain registered through service and its hosting in another service does not affect your SEO, and the site where you host the files of your website does not matter directly either.
Your hosting service allows loading your pages a bit slower
If you get a cheap and shared hosting, you will not get an optimal charging time, and slow charging time is bad for your user experience and SEO.
Your hosting service is not secure.
The type of server you hire may have security problems. And because the security of a website is a ranking factor for Google’s search algorithm, unsafe hosting is always bad for your website’s SEO.