ProphotoRGB wrong gamma in Photoshop

Have just iuninstalled and reinstalled LrC and reset its preferences.  No difference.

No difference.  Same display problem in Photoshop.

Will do.

Try a new display profile making sure it's V2. Any difference?

Recently profiled monitor with Calibrite's Colorchecker Display Plus using their current profiling software.  I am using an iMac Pro with Mac OS 12.6.6, LrC 12.3 and PS 24.5.  I am seem to recall that Calibrite Profiler defaults to building a version 2 profile.  I want to emphasize that until yesterday I had no problems and nothing has changed hardware wise since yesterday.  The only thing I can point to as being a problem is the way Photoshop, which just had an upgrade, is displaying the file.

Here's my current workaround.  I send a file from LrC to PS.  It displays incorrectly as seen in the above screen shot (the darker, oversaturated image is the incorrectly displayed one).  From the Edit/Assign Profile menu I select Prophoto RGB Gamma 1.4 (all the various profile types are available from a pulldown menu).  I then make muy changes, revert the profile to the default Prophoto RGB which has a gamma of 1.8.  When this is saved back to LrC, it is a match for the original file.  If, however, I leave the profile with a gamma of 1.4, when saved back to LrC the file looks washed out.

If there's any other information I can give to help debug this situation, let me know, and thanks for your contributions!

Postscript:  assigning the Prophoto RGB profile with gamma 1.8 leaves the image in its incorrect appearance.

Tell us how you've calibrated and profiled your display. Are you using hardware and an instrument, could you be building a V4 (version 4) ICC profile there? 

All your color settings and LR settings like fine. 

These are my External Editing settings for LrC and my Working Space settings for PS.  It is possible to assign a profile with different gammas for ProphotoRGB.  I mean, it's confusing, since I've been using this setup for years and suddenly this morning I get a difference in the display characteristics of an image between the two applications. And the same holds true for every file in Lightroom Classic.  I tried downgrading to an earlier version of Photoshop and that did no good.  I also tried resetting the Photoshop prferences.  That made no difference.  I then sent my Lightroom files, via Edit in function, to the app Exposure 7, and they looked fine.  This seems definitely to be a Photoshop problem.

Got zero to do with the gamma of the Working Spaces. In color-managed applications, they can mismatch (between Working Space and even the display TRC). Something else is wrong on your side. You're producing a document that is either untagged or incorrectly tagged, so we need to know more about what you're doing from LR to Photoshop.

There was a bug in an older version of Lightroom Classic, over a year ago that sent images from LR to Photoshop without the correct profile assigned. Make sure you are using the most current version of both Adobe products; that bug was fixed long ago:
Lightroom Classic: Editing raw file in PS from LR loses profile

[See here for how to reproduce the bug and an easy workaround:

https://community.adobe.com/t5/lightroom-classic-bugs/p-lightroom-classic-editing-raw-file-in-ps-from-lr-loses-profile/idi-p/12419751

The working space in Photoshop doesn't matter. The image will open in whatever color space you set in Lightroom Preferences > External Editing. This is what "Preserve Embedded Profiles" means.

ProPhoto RGB is gamma 1.8. Where have you found a 1.4 variety?

Please show a screenshot from Photoshop showing both "wrong" and "right". Are you using an old version? There was a bug a while ago that failed to embed the profile correctly from Lightroom, and the fix was to assign the profile in Photoshop. But that bug was fixed a long time ago.