It's 100% this. Anyone who's run a website or web app for any length of time in recent years and makes a habit of inspecting their logs will quickly realise that they're being scanned by bots looking for vulnerabilities multiple, or even many, times per day. The search for vulnerabilities is entirely automated and will pick up any domain that has a website or web app attached to it.

One those vulnerabilities are found, the hackers will pounce, and, whilst ransomware is one potential outcome, they might instead do all of the kinds of things GP has described. They don't care what the site is for or what industry you're in.