The tag itself is not insecure. It's just a tag in an HTML file.
What it does, though, is provide direct/immediate information about your the software you are using and thus can be used by hackers to select which of their hacking system to use to penetrate your system.
Without that information they would have to run probes and it could take a long time. Also with advanced web firewalls, you could detect such probes and block the IP address (Some people say blocking IPs is not a good idea, my experience is that it works wonders.)
Note that a tag which only gives a name is rather safe (i.e.
content="Wordpress"). If the tag includes the name, version, build date, etc. then it becomes really easy (i.e.
content="Wordpress 1.2.3 May 13, 2019"). So in your example, it is perfectly safe. Especially if your generator is proprietary and you use it for one or two websites (opposed to Wordpress which is used for million of websites.)
What is a probe?
Whenever you access a website you can detect which CMS was used to generate it by looking at the HTML contents.
- Wordpress uses paths that include
wp- as an introducer.
- Drupal uses
Every single CMS is going to do the same sort of thing for all the websites that use them. However, detecting the version is harder. You have subtle differences which will tell you but it makes the hacker's life more interesting (to my point of view--but read harder).
So hiding the
generator's tag makes no difference if you just have the name of the CMS in there.