<link rel="stylesheet" href="https://xxxxxxxxxxxxx.com/xxxxxxxx/css/app.css">
<iframe id="original_app" src="https://xxxxxxxxxxxxx.com/xxxxxxxx"></iframe>
You may refer to the Blogs as below, and I hope they can help you solve your problem.
Add Web Content to Power BI Dashboard
And I found an issue like yours, issue: Report Tooltips are not rendered correctly in PowerBI Embed
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
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