EDIT: POSTED BY MISTAKE. MAY BE DELETED.
In the 3.4 manual I found this:
Normally exposure adjustments should come before input color profile in the pixelpipe, and color adjustments should come after.
When I import a photo with scene-referred I get this:
As you can see, exposure comes after input color profile, not before. Is this wrong?
https://www.darktable.org/usermanual/en/module-reference/processing-modules/basic-adjustments/
That shows that the exposure module was activated at some time after the input color profile module was activated. However, this does not indicate the order in which the modules are applied in the pixel pipe processing. The pixel pipe processing order is shown in the right-hand panel, and there you will see that the exposure module is indeed applied before the input color profile.
You’‘re watching the history. You simply changed exposure later and so its later in thenhistory. The oixelpipe order is in the right module list
Right you are and I know this stuff. :-{ That beer I had a little while ago must have muddled my thinking. 
Can I delete this thread? Feeling very sheepish…
It’s a common mistake, so no need to feel sheepish. Leaving the thread here may help others who come to contemplate the same question…