Your forum software asks users to allow it to run arbitrary javascript inside a “Web Worker”. As is typically the case with these invasive scriptlets, it claims they’ll only be used for “push notifications”, but the actual WebWorker system is not restricted to notifications, instead, it can do anything doable inside javascript, even when the user is not on the website. These scriptlets also are often self-updating, which means a compromised “notification server” can be used to launch attacks against people’s computers. In short, this is a fairly serious “miss-feature”, which a privacy-oriented, freedom-respecting company ought not use.
There is a standard format for push notifications, which people who want them can use (and your website probably ought to offer): RSS.