2021.04.14 19:33 "Re: [Tiff] 4.3.0 release ?", by Even Rouault
From your earlier cmake invokation, it seems you did use -Djpeg12:BOOL=OFF, so tif_jpeg_12.c shouldn't be compiled.
Perhaps you need to clean your CMakeCache.txt if you refreshed your libtiff clone from an earlier version (there have been changes in the CMake support)
Could you also show the report displayed by cmake when configuring the project, in particular the line
-- JPEG 8/12 bit dual mode: Requested:OFF Availability:FALSE Support:FALSE
My software is free, but my time generally not.