I am so disappointed by you @Opera-Security . Because it also happened after I had wiped it from my MacBook and installed it again.
Setting DuckDuckGo as my primary search engine, made all the distinguished security active and had sync off.
So, no malicious link from history and no such behavior in Vivaldi.
Actually this drives me out. I trusted you, I even defended you, but that's even more than annoying, that's toxic.

I'm a little annoyed, suddenly. Can you explain this behavior, @Opera-Security , please:
I'm typing the word "deezer" in the address bar to make a search for it in my standard search engine DDG.
The word "deezer" will be auto-completed in the address bar to "deezer.com". I click into the address bar and delete the .com, with only having deezer staying there. In the left end of the address bar I'm having the DDG favicon.
But now: When I click enter, I won't land on DDG with search results for Deezer, but I'm taken through a tracking site the eventually leads me to the French homepage of Deezer. Which is strange anyway, because I'm located in Germany.
I made a clean install this morning and haven't gone to a suspicious site since then. So in all probability this behavior comes from Opera and isn't happening to any other search items, except for Deezer.

@Opera-Security Thank you, that's very kind of you to answer my post so exhaustively.
There's a lot of rumors about Opera if not even hate against it on some forums. I don't believe it. Still, I ask questions and saw your initial post.
I wouldn't use Opera if I wouldn't trust it. So thanks a lot for reaching out.

I'm very glad, you're bringing this up. It's good to know you're looking for transparency, because that's what we users deserve. It's on the same level as your debunking the spyware allegations a while ago.
So generally my acclaim to your post here, thank you. As I said, I'm happy with you bringing thus to our attention.

But if you don't mind, I would like to give some honest thoughts about the things you say. Having a longer experience with the Opera browsers on desktop, Android and iOS I see, there are some points to mention here.

First of all, it's really great that you can toggle off a lot promotional things in the browser. You also ship ad blocking and track protection even with uBlock Origin lists. That's great.
But if you install Opera for the first time either on Android or on desktop, you'll find a lot of stuff enabled by default which you have to opt out and not opt in. Let's name a few: newsfeed, promotional suggestions, weather forecast, Cashback etc. I really would prefer if I would be asked if I would opt in (I get, you have to earn money!). Especially as you promote Opera as a privacy (respecting) browser, which it isn't exactly.
The other thing I have to mention: After a fresh installation it's quite nice to see, that ad blocking is turned on (with some default exceptions like Google, Facebook and others). But with tracking protection turned off by default, although I consider this even more important than the first.
I know it's riding on the blade: on the one hand giving user choices, on the other hand making some money. But whenever I install Opera a new, I get the impression that all these privacy opt outs (shouldn't they be opt in?) are shattered all around the settings and you'll stumble upon them every now and then. I sometimes think, I haven't yet found each of them.

So in the end, concerning privacy I generally would trust you, but not totally so. You still collect a great amount of data, don't you? And some things in this blog and your privacy policy stays vague in this respect. Nevertheless, Opera is a great browser and I only wish you could even make it better.