It depends on the country really. Mrna vaccines require a certain temperature and can only be above a certain threshold for limited time, in countries like Brazil or others nations in development it's easy to imagine that this isn't followed 100% of the time and sometimes pass more time than they should in certain room temp.

I'll give an example, IIRC France said 20% of the doses were lost because of it but they discarded it. In Brazil we magically could do better than France by estimation of our own government and only 10 % would be lost. Do you really believe we lost less doses than France? We probably lost the same as them or more and applied them anyway