This is theoretically possible but practically infeasible for AES-256.
Recovering source code for a project where the original files were lost. Security Auditing: sourceguardian decoder
If SourceGuardian were to cease operations, users relying on their encrypted scripts would be unable to update their loaders for future PHP versions. This creates a "vendor lock-in" scenario where the software effectively becomes abandonware. sourceguardian decoder
If you are a developer using SourceGuardian, you should not rely solely on the encoder for security. Assume that a determined, well-funded adversary might eventually attempt to decode your files. Use multiple layers: sourceguardian decoder