This has been there since the Big Bang, so it is not urgent, but nevertheless is kind of a fly on a white wall.
The compiler always shows a warning when it encounters the first [async] statement.
The program compiles and runs, so the effect in the running application is nil, but the warning always appear.
Perhaps this could be put on the development list.
This must be an issue in the OmniPascal LSP, so we will take this up with the author of OmniPascal.
Thank you.