Mineshafts can generate with light but without any torches

So... Been playing minecraft snapshot 21w07a, just exploring a grimstone cave when i found a mineshaft with lights.
Was searching for the source of the light there was nothing, no torches.
I left the world then rejoind the light was gone.

It's a weird glitch and it might affect in the experience, that's why i'm sharing it.

1.16.5

Seed: 7437479687689956085
/execute in minecraft:overworld run tp @s -129.38 35.00 877.42 89.55 -11.55

21w08b

Seed: -1601601017667666262
/execute in minecraft:overworld run tp @s -327.54 -31.00 289.77 -1080.91 6.90

Video: Mineshaft light without torch.mp4