I tried to refresh my memory from previous threads, and I think the general trend has been to recommend (as seen in sibling comments):
https://modernc.gforge.inria.fr/
https://nostarch.com/Effective_C
I've also seen the older:
https://www.oreilly.com/library/view/21st-century-c/97814493...
Mentioned.
There's also Architecture of Open Source Applications, which can help with starting to read some larger code bases, some of which are in C: http://aosabook.org/en/index.html
And there's a general recommendation to go read the source code of the Redis cache/db.
Finally i came across a mention of this short article on gdb (nb: mention of TUI text ui should probably have been in the top, not a foot note):
https://www.recurse.com/blog/5-learning-c-with-gdb
I feel I'm missing a book that has come up often, but can't think of which one.
I did like zed Shaws learn c the hard way, but I'm afraid it's getting a bit long in the tooth: https://learncodethehardway.org/c/
It's like telling someone that SICP is the best way to learn Scheme. Maybe, but lots of people learn differently.
Unfortunately I don't have good suggestions myself, but at least they won't feel bad if K&R isn't their cup of tea.