This seems to be about the Vivaldi Forum posts (and images) being indexed by search engines. There's nothing to be done about this, unless the Vivaldi team decide to not have this forum being indexed, which is possible, and if they did the posts would soon disappear from search results. But I strongly doubt they will ever do that, as having the forum and its posts indexed is very useful for people searching for solutions to Vivaldi issues.
Google does have some tools but I think in this case it would not work.
https://support.google.com/websearch/troubleshooter/3111061
https://www.google.com/webmasters/tools/legal-removal-request?complaint_type=rtbf
However, if you have a site you control yourself, you can use robots.txt or HTML meta values to tell search engines to not index your site. Most serious search engines will respect this, and will also remove previously indexed content if the site changes its Robots policy.
https://en.wikipedia.org/wiki/Robots_exclusion_standard
For the Vivaldi Community blogs, there is a SEO plugin to control SE indexing if a user does not want their blog indexed:
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