Hi,
The cost of Azure SQL Database is comprised of multiple different components, not just amount of storage used. It depends on purchase model, compute tier, service tier, hardware type, storage/compute/bandwidth usage, redundancy option, license option. If you look on Compute + storage blade of your SQL Database, what options are selected?
Please look at some of the other views in Cost Analysis so that you can see more details for the charge. For example, navigate to your subscription in the portal -- Cost Anaylsis, click View -- Cost by resource. Click the arrow to the left of the line for your database to see more details for the $0.25 charge.
I'm guessing this is Serverless database and the $0.25 charge is for vCore seconds used, but that is just a guess since I don't have enough information. If you are still unsure of the charges after reviewing above please post screenshots of details from Cost Analysis and Compute + storage blade and I will assist further.
Please click Accept Answer and upvote if the above was useful.
Thanks.
-TP