Hi René, 

The TelerikTooltip component takes the string as-is from the title attribute. This means that the rendering context of that string is now HTML so \n and \r type of symbols won't render anything, you'd need a tag (like <br />) to render a new line.

In Blazor, however, to render HTML, you must use a MarkupString. We do not do that because that could be a potential security (XSS) attack vector.

If you need such complexity, I recommend using a template where you can prepare the desired content - create a MarkupString, ensure there are no scripts to be executed, transform \n \r characters to <br /> tags, anything else you need. Here's a basic example: https://docs.telerik.com/blazor-ui/components/tooltip/template#markup-from-generated-string

Regards,
Marin Bratanov
Progress Telerik