It appeared today as well...
I clicked and in my case it leads to "https://alitems.com/g/1e8d114494a47a83735c16525dc3e8/?ulp=https%3A%2F%2Fsale.aliexpress.com%2Fpl%2F__pc%2F20181111_main.htm&subid=11.11.2018_TB_PL"

The link (or its ending) may be different depends on what country are you in.
I found the link in opera_browser.dll among many others. From what I see the link should appear only in:

• Poland
• Russia
• Ukraine
• Belarus
• Kazakhstan
• Czech Republic
• Brazil

The link can be found in 56.0.3051.99 but not in 56.0.3051.52, so it's brand new.

Disabling "Receive promoted Speed Dials and Bookmarks" - doesn't help
Removing default_partner_content.json - doesn't help (I replace this file on each update to unlock custom search keywords)

Disabling sponsored content doesn't work with this. And closing it using "x" seems to only disabling it for 24h or so. I can see it for 3 days in a row now.

EDIT: New lead. I clicked "x" on mine today, so I can't check it, but ... I noticed a new file in Opera resources folder (mine is: c:\Program Files (x86)\Opera\56.0.3051.99\resources) called partner_speeddials.json. It contains urls to Aliexpress icon and site and many other partners (sic!). Can someone try to remove it and check if the Aliexpress bar is gone? I can only confirm that Opera starts without this file just fine.

Same here. I closed it yesterday but it's back today.
It's so ironic that with new version they added an option to disable sponsored content and at the same time they add more ads that ignore this switch. Especially after mods here denied the claim that Opera becomes adware browser.

How come Opera on the homepage says it's "free", same thing on Wikipedia it says it uses Freeware licence while clearly this all means it is adware!

@leocg Is that all Opera staff have to say in this topic? I guess they just wait until all of us will calm down and get over it just before new ad will appear again.

@deestonic I confirm, this is very frustrating! If you can't figure out why Opera has a single digit market percentage - now you know why!

@leocg Like I said, CSS is blocking it from displaying. Now I have just a white background

Basically any animated background I choose is disappearing after the update.

1. Open speed dial
2. Set animated background
3. You can see background changing on open speed dial
4. Open new speed dial - ok
5. Open new speed dial - gone
6. Open new speed dial - gone
7. Open new speed dial - gone
   etc.

It looks like it's hidden using CSS:
<div class="wallpaper animated" style="display: none;">
when I remove display: none; it works fine

Static background works ok.
53.0.2907.68 / Win7

I installed and connected Opera Touch on the first day, synced with desktop version, checked few things and left it for now. Today I noticed that I have some random notes in My Flow. While I'm 99% sure the first one is not mine. Maybe I tested it but it's odd word to test. But I'm 100% sure the 2nd one is not me. It just popped while I was working on something else just now. I definitely didn't have such text in my clipboard.

Is the connection secure? Some strangers can send me notes?