When I created my world a few years ago in 1.14.4, there was this weird chunk out at sea that got no direct sunlight. The only light this chunked receives was from adjacent chunks. Since then I have updated the world to the latest versions and have looked at the world seed in a creative world. While the chunk lighting error doesn't pop up in these other worlds, I thought this should be brought up.
Thank you for your report!
However, this issue is Invalid.
Your game, launcher or server is modified.
If you can reproduce the issue in a vanilla environment, please recreate the issue.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the creator of the plugin or resource pack.
If you have problems on large servers, such as The Hive and Hypixel, please contact them first as they run modified server software.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki