How does synchronous rendering affect SEO?

Question

JavaScript

I'm currently redoing a store.
I know that search engines do not particularly support asynchronous rendering.
I want to entrust the rendering of most of the site to vuejs.
At the same time, the page frame itself will give the backend,
I also plan to give the data for the pages in the form of json inside the page, which the application will already process, so that there are no asynchronous requests.
Interested in whether search engines are now able to handle synchronous rendering?
I would like to find some proof either to confirm or to refute.

Answer 1

I have a test site for experiments, I
specifically tried to load spam into it with Ajax - Yandex does not care about these Ajaxes, this is stupidly not in the saved copy