Since your investments are held by Trading 212 EU GmbH, they benefit from protection under the Bafin regulatory framework, and 90% of these investments are also protected by the Compensatory Fund of Securities Trading Companies (Entschädigungseinrichtung der Wertpapierhandelsunternehmen - EdW) up to €20,000 per person. It does not protect the value of your investment against price fluctuations due to market movements, but it protects you in case Trading 212 can no longer meet its obligations, e.g., due to insolvency, where you have no access to your assets.
Learn more about how the EdW works
here.