According to your graphs, it seems to have been a handful of cases prior to December. I must admit I know nothing about the covid situation in the Seychelles, but to me it looks like they have had good control of the borders. Some few infected people have arrived, but due to a good quarantine and/or test regime (and/or sheer luck) it never got out of hand. (I know of towns in Norway on the same size, but with a free flow of domestic transportation where they've done a pretty good job on keeping things under control until January 2021).
From around December the situation internationally has changed a lot due to new mutations. With new mutations, and only a full lock down can prevent an exponential growth of new cases.
To me it seems very likely that this wave of infections comes arrived from abroad and entered Seychelles in December.