Whenever I switched to 1.16.5 release candidate 1 today all my candles, and I think my copper disappeared.
Linked issues
duplicates 1
Comments 3
To restore your backup, press the "open backups folder" button, find the most recent backup file, unzip it, and move it to your "saves" folder
Sorry if I'm missing something here, but for some reason when I loaded the backed up version into Minecraft version 20w51a (the other snapshot) the candles and other things were still missing. It seems like the light sources for where the candles were are still there though. Edit: you don't need to fix this I'll just submit it to the support forums instead.
See MC-211308