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Obviously don't click on the link - that is more likely to install malware rather than anything else.
If you can work out which app is responsible, uninstalling the app will fix it. Most likely is something you installed within the week or so before this started, though an update or a change in an ad server might also be responsible. You don't say where/in what app this occurs, which might help identify the cause. I'd certainly clear caches of all browsers. Apps installed from third party sources (i.e. other than the Play Store) are more likely to be the cause.