Hi @Shailesh Jaiswal ,
According to my research and testing, unfortunately, there is no official documentation pointing out the functional limitations of SharePoint Modern Script Editor Web Part.
As far as I know, the Web Part is similar to the classic Script Editor Web Part and allows us to place arbitrary scripts or HTML on modern pages. Per my test, we can use HTML, CSS, JavaScript/jQuery, JSOM together in Modern Script Editor web part.
Hope it can help you. Thanks for your understanding.
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