AdF.ly is a famous URL shortener very similar to shorte.st that gives the user money when a link is shortened with it. The site itself isn't malicious, but the advertisements may be.
On the user's PC, it may open pop-ups if the owner of the link chooses so. There are 3 types of ads, pop ads, interstitials, and banners. The interstitials can be avoided if the user simply waits 5 seconds and clicks the "skip ad" button. The banners, being less intrusive (and common), can be avoided by clicking the red X in the top right corner of the screen. Pop-up ads may be simply closed. The person who made the shortened link sometimes links to scams, like the Brit method. This may also open Play Store links on mobile devices if the link owner chooses so. It also redirects the interstitial page to a random website after a certain amount of time. The push ad page may also create in-page toasts.
AdF.ly, depending on the shortener's decision, requires the user to click "Allow" on 2 notification dialogues The first is a fake dialogue that may sometimes display a dark themed page with a blue circular button with white text "Block" on it or a blank page. The page title may flash between the URL of the page and "## ##" This title was supposed to be "## Allow Notifications ##", but only the # remain. In some cases, it still appears. The second one is a real dialogue, which when "Allow" is clicked, the browser may display notifications of varying topics. When these are clicked, they do nothing. If the link owner decides so, they may block access the destination for users with ad blockers. Otherwise, the warning will still appear, but the user may still continue to the destination.