Steps to reproduce:

1. Place down a light block.
2. Change the light level of the block.

It appears that one texture (for example, the level 15 texture) and the next texture (for example, the one for level 0) are rendered at the same time.

 I was able to reproduce this on four different devices:

1. My main PC (Intel Core i7-10700 and RTX 3060)
2. My M1 MacBook Pro (Apple M1)
3. a Lenovo ThinkPad E490 (Intel Core i5-8265U and Intel UHD Graphics 620)
4. a HP EliteBook 745 G6 (AMD Ryzen 5 3500U and AMD Radeon Vega 8)

Videos are over 10MB, so watch them here:

https://1drv.ms/u/s!AgbwzdRfDSq_gfogdlch18uEnip7Zw?e=owqEy8