I have an already configured VPS server in Hetzner. I'm pretty happy with it. I have it configured with yunohost (a Debian "layer" that allows you to easily install services). Now I'm planning to run a NextCloud service, but my current server is not capable to handle it with it's current capabilities.
For the same price I could scale my current server or spin up a new server with the same capabilities and dedicate it to next cloud.
The disadvantages of spining up a new server, is that I have to configure another server and secure it, but the advantage is exactly on the same side: I will have a second server in case something fails or I want to "scale down" to save costs it will be easier.
Even if I just scale up the current server, I will have to add an extra disk and configure the server to use it, so I'm not sure about the advantages of each one.