MGS error in fresh install

I just installed Magento 2.3.3 with a theme which includes MGS Frontend Builder.

If I try to open Catalog – categories or products
Try to login as a customer or just try to change the configuration to flat products and categories I am getting this error…

Does anybody know how to fix this error?

Fatal error: Declaration of MGSMpanelHelperSwatchesData::getProductMediaGallery(MagentoCatalogModelProduct $product) must be compatible with MagentoSwatchesHelperData::getProductMediaGallery(MagentoCatalogModelProduct $product): array in