Undefined variable error appears when trying to access a global variable defined in a separate file
This may be related to ...
https://github.com/robocorp/robotframework-lsp/issues/641
The red squiggly line appears when trying to access a global variable defined in a separate file:

Create a robot file test_a.robot with the following content:
*** Test Cases ***
Set Global Variable ${thisISGlobal} globar var test
Attempt to refer to the global variable from another robot file test_b.robot
*** Test Cases ***
Log ${thisISGlobal}
Python version: 3.10 vscode: 1.74.3 Robot Framework Language Server: 1.8.0
I see this same thing. I import a variables file but it does not take it into account.
VAR_FROM_VARIABLES_FILE is defined in ../variables.py which it correctly sees as a valid import.
@red8888 % variables are loaded as environment variables, not global variables (so, in your example it should really fail).