Why do the black and blue versions of the Redmi Buds 6 have a protective film while the white version does not?

Due to differences in production batches, the black and blue earbuds come with a protective film that should be removed before use, while the white earbuds do not have a film and can be used directly.
Images of the black or blue earbuds with protective films:
1. Stems with films;

2. Stems with films + front shells with flat films;

3. Stems with films + front shells with mesh films.

Images of the white earbuds without protective films: