Google has grayed out, muted, its logo, for Memorial Day, again this year. It also applied an American flag under the search box with the message, "Honoring those who sacrificed." That links to the search results for [Memorial Day] on Google Search.
Here is a screenshot of the home page:
Google has done this last year, also in 2021 and 2020 and 2019 - but before that, Google had no special logo or home page treatment for Memorial Day.
Forum discussion at X.