I remember that 7 years ago, when I installed Thief Gold for the first time, the GOG version came with pre-applied TFix Lite. However, the support for TFix Lite has been discontinued for several years now, hence I was wondering if GOG moved to pre-apply the newest version of TFix instead of keeping the old Lite version.
From what I read on pcgamingwiki and other topics here this should not be the case: the GOG version of Thief Gold comes with TFix Lite and never presented the non-Lite version.

Since I need a fresh install of the game and TFix changes mantling of some objects, breaking some Fan Missions, I would like to have a version of the game only with the Lite upgrade to play. Can you confirm GOG has only TFix Lite?

Thanks for the confirmation. I checked the TFix Lite Drive folder indicated by the appropriate TTLG thread and indeed the current version was last modified on 2019, to support the latest New Dark version 1.27. Really happy to have been wrong.