German real estate investment giant Vonovia slipped significantly deeper into the red last year as property values declined, reporting a loss in 2023 of nearly €6.8 billion ($7.4 billion). The company blamed the further devaluation of its real estate portfolio for the losses, which were reported on Thursday evening after the close of trading. Vonovia valued its rental property portfolio at around €83.9 billion at the end of December. A year earlier, the company put the value of that same portfolio at €94.7 billion. In 2022, Vonovia reported overall financial losses of around €669 million due t…