Hi there,
Search engine bots look for dates in various places, and it is there algorithms that decide what date to display.
There are two main places that dates are output:
1. Date meta in the form of meta tags or JSON-LD output in the <head> of the website. These are not visible to users.
GP does NOT do this. So if those codes are present then it will be from another plugin eg. an SEO plugin.
2. Date displayed in the post content.
GP DOES do this, and they can be disabled in the Customizer > La1yout > Blog.
If you a) remove any SEO date meta and b) disable the Theme dates then there should be NO dates for the search engine to find. And then the search engine will decided whether to not show a date. You should not need any other plugins to remove them.
If you’re not sure of the above, then share a link to a post on your site and i can take a look.