I have really noticed this glitch in the 1.16.2 first, but through this glitch all mined blocks are glichting through all blocks to the heightest block if there is any block over the mined block.
It happend to coal, cobblestone, diamonds and every other block drop that has an other block above it.
I wouldn't call it a serious bug, but it is a little bit annoying...
Thank you for your report!
However, we are already tracking this issue, and this report is a Duplicate of MC-184941, which is a report that has not been resolved yet.
If you want, you can upvote the parent ticket, and enable watching to receive any updates about it - if you believe you have any information that may be important for this issue, please leave a comment on the parent. Please also use the search function in the future to prevent duplicate reports.
Quick Links:
📓 Issue Guidelines – 🛠 Community Support – 📧 Customer Support – ✍️ Feedback and Suggestions – 📖 Game Wiki
💬 Mojira Subreddit – 💬 Mojira Discord