Check that you deleted files from the right account and reviewed Drive's Trash. After a large deletion, Google says storage totals can take 48 to 72 hours to update. Avoid deleting more just because the number has not changed yet.
You removed a batch of files, returned to the storage page, and saw the same number. That does not necessarily mean the cleanup failed. Work through these checks in order so you do not lose files you meant to keep.
Check the account before anything else
Compare the email address in Drive with the account showing the storage warning. A browser can have several Google accounts open at once. Keep the storage page and the files you are reviewing in tabs for the same account.
Write down what you changed and when. A short note such as 'removed old exports from my personal Drive this morning' is more useful for troubleshooting than repeatedly clearing unfamiliar folders.
Look in Trash and review it carefully
Moving a Drive file to Trash is different from permanently removing it. Items in Trash still use space. Open Trash, look through what is there, and permanently delete only the items you are sure you no longer need.
Do not empty Trash as an automatic troubleshooting step. If you are unsure about a file, restore it and inspect it first. A slower check is better than discovering later that the only copy of a document is gone.
Source: Google Help
Give the storage total time to catch up
Google's current guidance allows 48 to 72 hours for storage totals to update after deleting many files. Refreshing the page repeatedly will not speed that up.
If you have already reviewed Trash, pause before another round of deletion. Record the current total and check again later. If the number remains wrong after that window, use Google's storage help and explain what you removed, which account it was in, and when.
Source: Google Help
Check what is still using space
Return to the account storage breakdown. A cleanup can succeed while leaving the account nearly full if the removed files were small compared with the rest. Look at the change in space, rather than the number of files deleted.
If the remaining space is mostly useful Drive media, making those files smaller may be more helpful than deleting more documents. If the total comes from another service, work there instead. FreeUp only shrinks supported files in Google Drive.