The bug
Any block or entity that has just been broken, including item frames and the items in them, will often turn bright for a short moment.
How to reproduce
Make sure you are in the dark; it is more noticeable.
Break any block or entity that drops an item in survival. Use a tool if needed.
Look carefully, the bug is very brief.
Linked issues
is duplicated by 19
Attachments
Comments
I don't know, it seems like a weird thing to add if so. It bugs me, no pun intended.
This is similar or same as MC-166276
Confirmed for 20w14a

This issue duplicates MC-166768. But leaving open for now as it triaged/labelled and has a priority set.
Confirmed in 1.16-pre3.
Able to reproduce. Flash is so quick it might be intended?