You may want to not install this update for some time or uninstall it when you find it installed.
An upcoming FileMaker release may switch to use Edge/Chrome for rendering PDF documents, so this will get fixed soon by Claris.
Alternatively you can use our MBS FileMaker Plugin to render PDF pages (DynaPDF.RenderPage) and have them show as JPEG or PNG pictures in a container.
See also posting in Claris Community: Suddenly PDF are not shown in FileMaker (since today !) in multiple computer / different customer