My friend randomly went offline for a while and then unfriend me. The account is still searchable but the avatar has not change since then. It has been about 2 weeks.
I would assume your friend hasn’t player the game for a while, it happens, even I haven’t done that for months and only to test created avatars, you would probably need a different way of checking up on them… or ask someone if they can search for them and see if there is a difference in your displayed results like an avatar change which would probably indicate someone being blocked for example, not sure if that’s how it works on VRChat.