Views pages have weird caching behavior

This is at least major. This has the potential to confuse people + might break actual sites.

ok, I finally tracked the problem down due to how cache-contexts are calculated.

Lupus CE renderer correctly adds this cache contexts:
'url.query_args:_content_format',
'url.query_args:_select',

But the problem is the _content_format is actually not changed via the query parameter, but lupus_decoupled_ce_api actually changes it via the request attribute. That means, lupus_ce_renderer should expose this is a new cache context which works like getContentFormatFromRequest().,
> $default_content_format = $request->attributes->get('lupus_ce_renderer.content_format', $content_format_settings);