I got in touch with my hosting service provider to buy a dedicated IP address. Once I made the payment, I verified the address using specialized services. These services provided a list of websites that are linked to the IP, which varied with some websites appearing more than once. I'm unsure whether I have been given a "clean" IP or if it's being shared with someone else.
How can I confirm this, and should I trust my provider or the IP check services?

Would you like to obtain an IP that hasn't been used before?
but, I doubt such IPs exist anymore. The key aspect is to ensure that your IP isn't included in the "black" IP lists of relevant monitoring agencies due to spam being sent out from it, mainly through email.

We take the console, take any address from the list of strangers, write ping other_site.com and look at what ip this site is. If it is dedicated to you, then ask questions to your provider.
What is important is not how many domains were linked, but how many remain.

Thanks, I have taken your advice.
I did share an IP with the rest. The provider could not find a reasonable solution.
Took the address from another operator.