It definitely doesn’t matter if you play casually, but it doesn’t matter if it’s a regular game.

Because large-scale competitions value fairness, only rubber and blades approved by the ITTF can be used. If they are cut off, there is no way to prove whether the rubber has been approved. You can see that in addition to the trademark and name, each rubber has an ITTF logo and code. Only those with this code can be used in large-scale competitions.