I was referring to documentation i.e
It has below definition for Filtered aliases:
Aliases can hold a filter, which allows to select a subset of documents that can be accessed out of all the documents that the physical index contains.
These filters are not always applied and should not be used in place of document level security.
Can any one explain what does it mean when they say "These filters are not always applied".
My assumption is if we create a filtered alias , it should filters should always be applied.