Lost some notes on my MacBook Pro and can't find it again after unlisting notes from the "Apps on this Mac Using iCloud"

When you turned off notes application box in Mac https://support.apple.com/en-in/guide/icloud/mmb1de40d9/1.0/icloud/1.0

But you had short of iCloud storage space , the step to be followed was increase the space in iCloud https://support.apple.com/en-in/HT201318 , was optimisation feature turned as on , disable it .

Once again you turned on notes application the notes from iCloud server / if a gmail account was also configured will start syncing having high network speed .

In notes preferences do the settings accordingly , first click on drop down arrow of default iCloud account ( a ) first choose iCloud . let the complete data from iCloud server sync ( b ) once completed select gmail then on my Mac .

Seethe article https://support.apple.com/en-in/guide/notes/apd97da26aed/4.7/mac/10.15

Search notes on my Mac section in your notes application ( on my section will be on bottom end of side bar ) .

Do you see a Recently Deleted folder in the Notes application or at iCloud.com/Notes using a computer browser?

Documents or notes see if you ever had set up time machine see the articles https://support.apple.com/en-in/HT201250

https://support.apple.com/en-in/HT209152

Are the notes still available in iCloud?