devtrackers.gg
Yes, there was probably a mixup in the platforms, should be corrected now. However, if your server is receiving the server message, it is one of the servers affected and will be taken down at the given date.
"Temp" is short for temporary, meaning the server is created for a limited amount of time. Player numbers can fluctuate, a good example was us entering the Xbox Game Pass, which made the game available to a huge range of players who wanted to test it. Obviously not every person who tries a game, stays with it. So now it's time to close some of those temporarily created instances again, to bring players closer together. There is still more than enough space to cover all of our players on official servers though, so you will be able to find a place to play.
In general we have the possibility to make temporary servers permanent, but considering the trend of players moving towards customized experiences on Community servers (which we wholeheartedly support), this is unlikely to happen.