i would recommend having your primary monitoring on a separate vps to any other essential hosting services.
ideally on another network / datacentre.
something like the cx23 vps at hetzner is way more than needed to run uptime-kuma and would only be 3.49 euros/month. so you could easily run a few other non-essential services on that vps as well.
if it's on the same server, it would either not notice any network issues connecting to services on the same vps, or problems on that vps could stop it sending any alerts, so you wouldn't know there's any problems anyway.
you could (should) also add an instance of uptime-kuma on a 2nd server, could easily go on one of the hosting servers, panel server etc.. and have this instance just monitor the main uptime-kuma instance and alert if there's any problems with that..