What does the blue-green zone on the bitcoin Rainbow chart mean?

Excuse me, could you kindly explain what exactly does the blue-green zone signify on the Bitcoin Rainbow chart? I've been noticing it quite frequently but have been unsure of its significance. It would be immensely helpful if you could provide me with a clear and concise understanding of its role and what it represents in relation to the overall Bitcoin market dynamics. Thank you in advance for your assistance.