FileMaker Pro 19.1.3 and FileMaker Server 19.1.2 are compatible with macOS Big Sur 11.0 with no known issues.
FileMaker Pro 19.5 is compatible with macOS Ventura
** Windows 11 is supported with the release of FileMaker 19 products.
Effective September 2021 - Crate Pro 6 is released with FileMaker 19. Customers on older releases should request upgrades if upgrading their operating systems.
Normally there is backwards compatibility of one to two FileMaker versions, but not for OS 11