What you are looking for are legendary and master lost sectors. Those rotate daily and only show up on map if you’ve completed the lost sector they show up in. You will have to look up the lost sector each day then go clear it once normally for the flag to spawn at entrance of lost sector. Another thing is fourth horseman catalyst is not from those legendary lost sectors since bungie decided not to just go ahead and add it to them when they added more catalysts back to game.

Pretty sure they were removed after arrivals or worthy. Only way to get back into them is probably by glitching if they haven’t been removed.

That is a different season your talking about and bunkers used to be everywhere in planets. So you can’t find bunkers anywhere.