Why is this an issue?

When an identifier is too short, it negatively impacts readability. To figure out the meaning of this meaningless variable name, all of the relevant code needs to be read and understood.

This can be particularly frustrating in Delphi, as variable declarations may be fairly distant from its usage.

How to fix it

Use a longer and more explicit identifier name:

var
  M: string;
begin
  M := LoadMessage;
  // ...
  Log(M);
end;

var
  Message: string;
begin
  Message := LoadMessage;
  // ...
  Log(Message);
end;