Gurkas have guarded before….
https://www.forces.net/services/gurkhas/behind-scenes-gurkha-engineers-queens-guard-duties
https://www.aviation-defence-universe.com/british-gurkhas-take-up-london-guard-duties/
Not that I'm aware of, but the seal/crest on the gate seems to have been missing since being damaged by a delivery driver, last year.
https://metro.co.uk/2019/10/02/unicorn-knocked-buckingham-palace-gates-delivery-lorry-10848862/
https://www.newsflare.com/video/316271/royal-crest-missing-from-buckingham-palace-gates-after-the-unicorn-damage-by-delivery-lorry>>9352615
Queen Elizabeth to Stay at Windsor Castle Indefinitely, Out of the Public Eye, Amid COVID-19 Crisis
The British monarch would normally return to Buckingham Palace in May, and be readying for summer events like Trooping the Colour—but this is not a normal year.
https://www.townandcountrymag.com/society/tradition/a32433193/queen-elizabeth-windsor-castle-coronavirus-indefinitely/
BAKER
Royal seal damaged and missing in 2019:
One of the Royal crests is missing from the North Centre Gates of Buckingham Palace after the Unicorn, representing Scotland, was severely damaged by an incoming delivery lorry on 1 October 2019.
https://www.newsflare.com/video/316271/royal-crest-missing-from-buckingham-palace-gates-after-the-unicorn-damage-by-delivery-lorry