The truth is usually in the middle. I don't think the franchise has had any thoughts about trading Lamar or that there's really even some major riff between he and Harbaugh.
But at the same time, yes, it's not overly difficult to see how its difficult to work with Lamar. He's not a diet/workout guy. Doesn't seem to have the film study obsession that some of the great QBs did, though I don't think it's a "problem". Doesn't have an agent so you have to work exclusively through him and meet whatever arbitrary timeline he has in his head. He has reported illnesses more than literally any QB I can ever remember. And it does appear he's quite conservative when it comes to playing through injuries. The "sleeping through film study" thing is nothing new. Heard that one plenty of times before.
Lamar has always been the guy who, while develops, seems to lean a lot more on athletic/physical talent than mental talent. And in most cases, that's fine. Because he's a unicorn in that spot. But he's not in "everyone's cup of tea" kind of guy.
If it comes down to Lamar vs John, they're picking Lamar. But Ravens fans truthfully have been "spoiled" to the level that they're not used to hearing this kind of stuff, because they're winning. Losing teams have these exact same kinds of conversations every year. When you're losing, there's always dirt to uncover and people to blame. It's happening in Detroit today. Its been happening in KC for weeks. There's more noise around losing teams than winning teams. Always.