This is a message I’ve received from Bricks support team:
Your website encounter a very special weird issue which is related to the global class DB.
There is one empty array inside the global class DB causing the global class style to get incorrect index and so the styles are generated incorrectly. We can’t replicate the issue locally and I believe you wouldn’t too. As a workaround, I can apply a code temporary on your site to fix the corrupted DB and remove it afterward.
The issue appeared again and the temporary code had to be applied once more. I decided to stop generating classes using BEM generator from ACSS and start creating classes in normal bricks way. The problem hasen’t appeared since.