[gghoop]

If I had to guess:

They think you're a poor performer in your assigned role and it's because you're too interested in the code. They assume you can do the job if they remove the distraction.

Or:

Your manager knows you want to go over to software engineering and if you appear to know and understand the codebase you could be poached to the other team.

Either way it looks like your manager wants you to fit the role you have been given and to stay there. The anxiety about linkedin points to this. You expressed preferences to be doing something else. You're a flight risk and they are trying to limit your options.

Edit in some unsolicited advice:

You don't need to quit over this but you should quit your job if it's not leading you to where you want your career to be, which it obviously isn't. The first 10 years of experience sets you up for your career beyond that and if it's going in a direction you don't enjoy you're going to be miserable in your job. Find a development job if that's where you want your career to go, there is no time to waste.

[lovatsofa]

Thank you gghoop