In the past, search engines had difficulty crawling and indexing websites created with JavaScript rather than HTML. While Google has claimed that the Googlebot is able to crawl and index JavaScript-based web pages without any problems, other search engines like such as Bing, Yandex, or DuckDuckGo can’t crawl JavaScript properly, making server-side rendering relevant for any application involving search engine optimization.
Server-side rendered HTML usually gets hydrated on client-side.