If you have your whole inventory full with something then hold CTRL+Q and clear your WHOLE Inventory all at once on the ground but when you pick it back up there is less of it.
Linked issues
duplicates
Comments

Thank you for your report!
We're tracking this issue in MC-116618, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
Does MC-116618 describe your issue?