Why is this an issue?

Omitting the type for inline variable declarations has a few downsides, including:

The lack of type information can make code harder to follow and understand at a glance.
Type expansion that occurs during type inference can lead to unexpected inferred types.
Wrapper types relying on implicit type conversions will not have those conversions invoked.

How to fix it

Explicitly specify the variable's type:

procedure Example;
begin
  var Foo := 123;
end;

procedure Example;
begin
  var Foo: Integer := 123;
end;