Leaked screenshots from Samsung's One UI 2.5 software showcase egregious lock screen ads that effectively prevent users from unlocking their phones for fifteen seconds. However, Samsung will only run these on some low-cost Galaxy A and Galaxy M devices. We should have more clarity on the matter once One UI 2.5 is released later this year.
https://www.notebookcheck.net/Samsung-will-allegedly-show-ads-on-some-low-cost-phones-with-One-UI-2-5.469387.0.html