Just to say, your DEV if its a real DEV environment is of course free and you cannot add capacity too it.
Now to answer your question.
In the Admin Center
-Click on Licensing
-Click on Dataverse (to start)
An image of our usage first) based on overall
now scroll down a little on same screen
Now click see all environments at the bottom
Now click on any environment, i'll pick The Gernaey Code. While it all says its within capacity let's take a look
Now you are on the Database usage by default, so scroll the screen down and you will see all storage tables and what they are doing.
FYI, Copilot takes a lot, there are other Trials that take A LOT.
Now scroll back up and click File and Log
When I click File and scroll down I see explaining how much space each table/resource type is taking
Same for log
You can further click on a link like WebResourceBase and get this
This will all show you where your data is being used. Now you will have to look across your solutions, what you installed (your own solutions + trials + purchased + Microsoft Free / CAT etc, people installing Sample Solutions etc.
And you will see what is doing what.
On the same screen at the top click Manage Capacity and validate what you assigned to it, validate what you set for Pull from Tenant Capacity etc
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey