In essence, the red channel looks good on the histogram because the histogram reflects the wide-gamut color space that Lightroom uses internally, whereas your monitor can't display that wide space -- your monitor is closer to displaying the sRGB color space. You will find if you look at an sRGB histogram that the red channel will be clipped.
The camera captures a larger gamut still, but for practical purposes you either want an sRGB-compatible image or you need to know that stuff like this can happen. How it will print is another matter entirely -- some printers could handle this, others not.
Here is a recent thread about this:
https://photography-on-the.net/forum/showthread.php?t=859118
If you want to get a visual look at how they relate, you can use either ACR (Adobe Camera Raw) that comes with Photoshop if you have it, or DPP (Digital Photo Professional) that is the Canon Raw software. Both of these tools have a switchable color space that is reflected in the RGB histogram (with DP it is in the RGB tab). You can watch the sRGB-tuned histogram as you tweak the Red channel brightness and saturation to tone things down (you may want to tone the whole image down a bit to start with -- it just needs playing around).
You can get the same results in Lightroom, but the histogram will be no help. The HSL panel will enable you to tone down both the Saturation and the Luminance of the Red channel. Like I say, you may need to work with some of the global controls to balance things out as well.
Hope this helps some!
