The Data State Inspectorate (Datu valsts inspekcija, DVI) is Latvia's national data-protection authority enforcing GDPR. If someone files a complaint or a third party reports drone filming, the DVI can open an investigation. GDPR fines can reach €20 million or 4% of global turnover.
Keep the two authorities apart: the Civil Aviation Agency governs the flying itself, while the DVI governs the personal data in your footage. A permission to fly gives no right to film people; that side of things falls under the DVI.