Conclusion: If this extent of vitiligo is regarded as a defect according to your social custom, that people find off-putting, then you must disclose it and give the suitor the choice concerning the marriage. This is better for you and for the suitor. You have to be patient and put your trust in Allah, may He be exalted, and Allah will grant you ease after hardship. We ask Allah, may He be exalted, to make things easy for you and to relieve your distress. And Allah knows best.