Well... it's complicated. I could list many possible reasons why programmers could be walking away from C but are you sure this isn't some bias or statistical error of the website doing those measurements?
Devoted my life to programming...
https://www.tiobe.com/tiobe-index/
The big 3 all took a hit, and I notice that the sum of all the deltas is -5.44% in a total that only adds up to 70%.
I just don't buy that everyone abandons the top 3 languages in concert, especially when there is no apparent 'new' replacement.
Languages #21 to #50 account for a further 20%.
Who knows, but I'm suspicious of methodology changes / data collection changes.
Read their FAQ
I smell the same thing happening again.Q: What happened to Java in April 2004? Did you change your methodology?
A: No, we did not change our methodology at that time. Google changed its methodology. They performed a general sweep action to get rid of all kinds of web sites that had been pushed up. As a consequence, there was a huge drop for languages such as Java and C++. In order to minimize such fluctuations in the future, we added two more search engines (MSN and Yahoo) a few months after this incident.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.