You relize that Garrison Monuments are broken from about 3 years now? I know this is old content and nobody cares about it, but some people still enjoy be there and some of those monuments were not easy to get back in the time. Why do you keep destroying old content and later completly not care about fixing it?
When you click on the monument it says EMPTY and you can’t change it.
Just to keep this bug report highlighted…
There is a (very) hot topic on US forum about this issue, so Blizzard is aware of it.
Will they solve it for an hypothetical “Warlords of Draenor Remix”? 
BTW, I earned my first garrison monument just a couple of months after Dragonflight release. 
Hi, speaking of achievements. Could we also fix this that was promised to us?
"In the past, we have displayed your account-wide achievement point total in some places (like at the top of your achievement pane) but only your character total in others (like in guilds).
With the introduction of Warbands, we want all achievements to be considered “Warband” achievements. You, the player, accomplished them, so you should not feel like you need to complete them on more than one character or feel like you do not want to play another character because they are missing achievements.
Given this, we are eliminating the concept of a character-based achievement score. From now on, a total Warband achievement score will be tracked and displayed instead. This score will be the sum of all account-wide achievement points plus the points from any character-specific achievements completed on any character."