You have a carrier phone. Therefore your phone has the firmware customized by Verizon for your phone. Samsung doesn't add pop ups or unwanted 3rd party apps but carriers often do.
More than likely the pop ups you are seeing is caused by some 3rd party app on your phone. Removing that app would stop the pop ups.
To add to what @LongHiker said, if Verizon put an app on your phone that in turn added Malware, they should not then be charging you $25/mo to offer you protection services. You don't *have* to pay them anything. You can use Malwarebytes. You can identify the problem app, by downloading Good Lock's Nice Catch and turning on "detect toasts" and "detect commercials" to see which app is causing the issue. Or you can just immediately uninstall any app Verizon puts on your phone. They have the right to put them there, per your contract, but you are not required to use or keep them. You can also make sure you have app protection turned on in the phone's security & privacy settings. I just want to add, also, that if there is something that commercial malware removers can't touch, than neither can whatever Verizon is using. They have no magical fixer - unless they caused the issue just to get an extra $25/mo from users. It is possible that you just did not hit on the right malware protector.
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