In 1 Corinthians 8:9, Paul warns your freedom must not become what to the weak?

Answer: A stumbling block

On food sacrificed to idols, Paul says: 'Be careful that your freedom does not become a stumbling block to the weak.'

“Be careful, however, that your freedom does not become a stumbling block to the weak.”— 1 Corinthians 8:9 (BSB)