I have got few blocks (custom and from some external modules), that are I believe dynamic (most likely cache disabled blocks).
When the page is rendering it initially fills those regions with span ids like these
data-big-pipe-placeholder-id with empty content in it.
And after a few milliseconds, it then renders the content on those blocks. This then shifts the contents within the page.
There is a new check by google for page/block shifts, they call it CLS (https://web.dev/cls/). I believe google will be penalising for too many block/content shifting websites soon.
How do I overcome this?