I maintain the DNS plugin for Vultr and I can say that it’s “safe”, but if you’re worried you should check their source code.
I believe it’s easier to have a vulnerability in the external provider’s API (for example, caddy-dns/vultr uses govultr) than Caddy. But I wouldn’t take things for granted if I was skeptical about these plugins.
I realized it happened with me whenever my computer was idle for a few minutes and the monitor turned off. Eventually it fixed itself, but it sure was annoying having to change the brightness back to the value it was before it went on stand-by.