I found this Blast article a lot more informative than the linked write-up. Excerpt:

Kimmel addressed the shocking end of "The Late Show with Stephen Colbert" on his Instagram Story, sharing a clip of his friend's confirmation of the news. He captioned the post with a direct message to the network, writing:

"Love you Stephen. F-ck you and all your Sheldons CBS."

Kimmel's words referenced CBS' iconic character Sheldon Cooper, whose life was depicted in two hit series, "The Big Bang Theory" and its spinoff, "Young Sheldon." The TV host appeared to be calling BS on the network's decision to cancel Colbert's talk show while promoting other programs.