Cover Block: Default height cuts off taller content published before 6.4

[iamtakashi]

This issue has already been mentioned in the PR #17143, but I thought it'd be good to open a new issue for it so that it won't be forgotten :)

Since the default value of the new setting "Height in pixels" is added to all the existing cover block in a site, taller content published before 6.4 gets cut off in the editor with the update. (6.4 is on the right)

This is a problem in large sites that have a lot of already published posts and page with the block, and I'm curious about the next step to resolve this if there is any.

[jorgefilipecosta]

Hi @iamtakashi, @allancole I proposed a PR that refactors the height mechanism #17365 it should fix the problems being faced.