Why is this an issue?

Delphi constructors should only be called on the class. A common error for new Delphi programmers is to call a constructor on an instance variable instead. This does not create a new instance of the object, instead being treated as a regular routine invocation.

If the instance has already been initialized, it will unexpectedly modify it by re-running the constructor.

If the instance is uninitialized, an access violation may occur (the constructor will attempt to set fields on uninitialized memory).

How to fix it

Call the constructor on the class instead:

procedure Example;
var
  Foo: TFoo;
begin
  Foo.Create;
end;

procedure Example;
var
  Foo: TFoo;
begin
  Foo := TFoo.Create;
end;