Are there any fees for credit apart from the interest?

For personal loans, the amount of fees offered to a particular customer depends on their personal credit score. The credit score depends on the customer's creditworthiness, up-to-date financial liabilities, credit history (behaviour, active and/or already repaid overdues) etc. Any and all fees are clearly stated.

For credit limit, there is a small monthly fee of 10 zł charged if you do not perform at least 10 transactions in a calendar month.

By the way, all fees already applied and related to your current Revolut plan are stated here.