Sending documents to a vendor's cloud is its own compliance problem.
UIDAI's Circular 14 limits where Aadhaar data may be hosted. RBI's Digital Lending Directions require that "all data is stored only in servers located within India" and that anything processed abroad is deleted and brought back within 24 hours. Most masking APIs want your documents on their servers.
What Aadhaar Masking does: Run it inside your own AWS account from AWS Marketplace, or on your own servers. Nothing leaves. Nothing to explain.