There are still guards at the palace.
Contrary to what people think the guards are not always from the Brigade of Guards in their familiar red tunics, sometimes they are from other units that have less ostentatious and more muted uniforms.
During the cold weather the Redcoats wear their grey overcoats which makes them less obvious to passersby.
Image from a few days ago. 10th April.
https://www.telegraph.co.uk/royal-family/2021/04/10/nation-mourns-military-pays-tribute-41-gun-salute-tribute-prince/