At the moment I am using this dev version of RT:
RawTherapee_dev_5.8-3002-g4d1711412_W64_znver2_210622
Though I think the described detail works the same way for all versions:
When I load a TIF file into RT it’s most often to compare that version to the original editing of the RAW file, so in such cases I have no need for at pp3 file to be created for the TIF - as I have no intention of changing anything in the TIF in that situation.
But a pp3 is created anyway, and the number of “formal” pp3 files build up for no reason and only add to my confusion.
I suggest that no pp3 file is automatically saved for a TIF file (and probably a JPG too) unless explicitly demanded. This could depend on the well known question: “Do you want to save the changes to mycurrentTIForJPGfile” - Y/N.
Alternatively - no changes of the TIF or JPG would delete the pp3 in the background - or the pp3 would not be created - depending on when this file is created in the process.