@neetesha Thank you for your reply. The link disappeared after maybe 2 hours. I didn't have to do anything. This has happened before. It is correct that I might have copied the link address at some point.
@sgunhouse, @yanta I googled more about this "preinstall data2" and found out it is an adware, not a malware, and I just remembered that a year back I did block this app's notifications because it was spamming random ads on my notification bar, it all makes sense now, I'm impressed this app found a way to annoy me again 1 year later by other means, I decided to force stop it and deactivate it yesterday, opera didn't open itself ever since, I guess it's solved.
Thank you two for helping