Hello.
Are you certain you are connecting to a server with correct shard? Aka if your character was on 3pp previously, are you connecting to 3pp?

I believe so. I had admittedly not played in about a month. I had left the launcher running when I opened the lap top. I closed the game, the launcher, and steam. When I opened steam to re-launch it needed the update due to Badlands coming out. It took 25 minutes to update, and when I launched the game my character and all my belongings were there. However when I went to load into the server I recieved the error regarding this server having a DLC I did not possess. This is the moment I went to all official servers to chose a different one. Once loaded my character had reset as if I had died.

All official servers wiped completely (character as well) for the 1.30 update, last I knew. It sounds like this is what you're describing.

Was that intentional? Seems illogical to wipe everyone's characters with an update. I assume then there isn't a plan to restore them?

Characters have always been wiped with new patch updates since DayZ was released

There's red messages at the bottom left of the screen in-game that warn you of this weeks in advance too

No plans to restore characters that were wiped with major update. This is regular occurrence