Lighting bug with pistons and piston loading blocks

When the head of a piston is a loaded block, a strange lighting bug appears, a shadow is generated at the beginning of the extension of the piston, see image.

I tested this bug in the next java versions:

1.16.3, 1.16.2, 1.16.1, 1.15.2 (without optifine and with the default config, in my tests, the brightness was in bright mode)