What I expected to happen was...:
lighting bug errors should no longer be as common in version 1.15
What actually happened was...:
At the time of exploding a reappearance nexus in the overworld, fire spread through the place and when the flames ended, there were traces of illumination even when there was no fire
Steps to Reproduce:
1. be in the dark or at night to see the bug
2. activate a respawn nexus and blow it up
3. then all the fire must be extinguished and traces of light bugs will remain
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Resolving as a duplicate of MC-166260 then.