Why is this an issue?

While Delphi is case-insensitive, casing of name declarations and references should be kept consistent to aid readability.

How to fix it

Rename the identifier to match the casing in the original declaration:

procedure FooBar;
begin
  // ...
end;

procedure Example;
begin
  Foobar;
end;

procedure FooBar;
begin
  // ...
end;

procedure Example;
begin
  FooBar;
end;