I believe those rifles they are carrying are considered “Jamamatics”. A cobbled up bullpup version of the AR-18.
Stupid looking bullpup & looks like it’s wearing foam pads to keep the gun from staining the uniform?
Its predecessor the FN L1A1 was called the “mechanical musket” and was not well liked.
IMO those palace guards would look far snazzier carrying WWI era Lee Enfield rifles. More of a match with those period uniforms.
I have a #1 MkIII Enfield & it looks and shoots like a dream. Blue steel & wood with no plastic. 100 years old & going strong (may that someday refer to myself!).