So, maybe this will be marked as WAI, but I couldn’t find a feature request or bug report on this topic. I mean, worst that can happen is nothing.
If you try to modify the Data of a Player the game just says „Unable to modify Player Data“.
To reproduce this, you just need to use a command like /data or execute store and will get the message.
Hopefully this will be „fixed“ soon!
Linked issues
Comments 2

Thank you for your report!
We're tracking this issue in MC-122102, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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
-- I am a bot. This action was performed automatically! If you think it was incorrect, please notify us on Discord or Reddit
Duplicate of MC-122102, which was later resolved as "Works As Intended".