custom filter is not worked on github pages about vreality64.github.io

[vreality64]

I think this code may be hint. config["gems"] are initialized with DEFAULT_PLUGIN values

# Given a user's config, determines the effective configuration by building a user
# configuration sandwhich with our overrides overriding the user's specified
# values which themselves override our defaults.
#
# Returns the effective Configuration
#
# Note: this is a highly modified version of Jekyll#configuration
def effective_config(user_config)
  # Merge user config into defaults
  config = Jekyll::Utils.deep_merge_hashes(MERGED_DEFAULTS, user_config)
    .fix_common_issues
    .add_default_collections

  # Merge overwrites into user config
  config = Jekyll::Utils.deep_merge_hashes config, OVERRIDES

  # Ensure we have those gems we want.
  config["gems"] = Array(config["gems"]) | DEFAULT_PLUGINS
  config["whitelist"] = config["whitelist"] | config["gems"] if disable_whitelist?

  config
end