Dear ANONYMOUS friend, your employer, i.e., the shop, had a staff of 20 employees in 2012, as stated by you. However, it appears that your employer provided incorrect information to the EPFO when applying for PF registration, stating that the employee count reached 20 from 01.04.2018 onwards.
Your employer is responsible for PF registration and should pay the PF dues from 2012 onwards. Your employer might avoid this responsibility due to the current inspection policy of the department. Unless someone lodges a complaint with the EPFO, they may remain unaware of the situation.
If you personally file a complaint with the EPFO, you could encounter trouble.
Please let me know if you have any questions or need further assistance.