Flesch Reading Ease - YOAST. Is it stupid or am I going crazy?

I'm done with it! I add SEO blogs and pages to a client's WP site and the bloody Flesch thing is driving me mad. It's not technical content - it's basic stuff. I'm a professional writer with years of experience but it's always whinging "very difficult to read' at me.

Ok, not ALWAYS but sometimes. I've dumbed down the content so much that it's reading like a toddler's board book!

Will it damage SEO to leave it red? I literally don't know what it wants at this point. I have my doubts that it's trustworthy because sometimes it's happy and sometimes it isn't and the content's not that different.