Up to v12.3.1 statements outside any special context or Module like
v=7;
f[x_] := x^2
created variables and functions within the Global context. Now in v13.0 they are created in CodeParser`Private context. I could not find any explanation about that change. Neither in Wolfram Blog nor in Summary of changes.
By the way: Syntax coloring for global variables doesn’t work anymore. They were blue as long as being undefined, then black. Now they stay blue since they are no longer within Global.
I tried several things to reproduce that strange context CodeParser`Private`: Running v12.3.1 at the same time, with and without Wolfram logon, with and without internet connection. No chance. I cannot get it again.
Maybe there is some automatic software update implemented with v13?
I have a Wolfram|One license. this contains Wolfram desktop. I run it on a Windows 10 Thinkpad Laptop-PC.
I don’t remember if there was something special when that weird context issue appeared. I tried it again with aborting something before the code above. No problem occured. Still Global` context.
I think we can forget about this issue. It no longer occurs. Sorry for the confusion I have caused.