Student or Learner
is this a bad expression?
please note that my goal is only to be able to communicate clearly and speak a nice and informal English.
What do you mean by a "bad expression"? It is a perfectly normal one, in the correct context.
"Whatever the situation is tomorrow, I am going to go to the game!"
I mean an expression that I should avoid using.
I think I have seen it a lot, but I have just searched BNC/Google and found very few entries for it.
Note how it is used (more often without 'is':
In order to ensure the best possible power and road grip whatever the situation, the Volvo S80 T6 and V8 models are equipped with Volvo's active All Wheel ...
Whatever the situation we find ourselves in, however unpleasant or bland, ...
2-bedded paediatric intensive care unit which offers parents the security of knowing their child is in safe hands whatever the situation or treatment. ...
Whatever the situation, it is the people themselves who have to resolve to meet the situation with courage and fortitude.
Whatever . . . .
It is what it is . . .
(Those are two expressions that might be considered offensive, depending on how used.)