Hello,
The "commitment" is just that, you "commit" to paying a minimum amount for 31days (100GB, 200GB etc...) to get the discount, any data above that will be charged for, source: https://azure.microsoft.com/en-ca/pricing/details/microsoft-sentinel/
Please note, the text at the bottom of the table for your evidence.
*Data ingested into Microsoft Sentinel exceeding the selected daily commitment tier is charged at the effective tier prices listed above.|
*
If this helps, please Accept the answer. Thank you