It is sooooooooo annoying.
You can see it in this attached image, it happens almost every time I edit in Photoshop and return to Lightroom. I have more examples.
Mac OS 10.15.3, iMac 27" 2018, Benq SW321C Photographer Monitor. Adobe Photoshop 21.1.1 Lightroom Classic 9.2
Same image in Photoshop:
"Reading through the jumbled order of replies, it's not clear that you've tried enabling the Photoshop option Preferences > Performance > Legacy Compositing, as suggested by Bob Somrak, and then resaving the image after making a trivial change. There is a bug in PS 21.0 and 21.1 that incorrectly renders the final image as seen by LR and other apps (PS displays the image correctly):https://feedback.photoshop.com/photoshop_family/topics/reproducible-bug-in-feathered-layer-masks-photoshop-lr-classic?topic-reply-list%5Bsettings%5D%5Bfilter_by%5D=all"
Re your sample TIFF, I don't see the symptoms when I open it in Mac Preview or LR. But some further testing shows that the bug only appears to occur when you open a raw in PS, add a feathered layer, and save it as a PSD or TIFF. If you reopen that PSD or TIFF in PS and force a resave, either by making a small change or by doing File > Save As, the image then appears correctly in LR and other external apps.
So it's the first time you open a raw and save as a PSD/TIFF that provokes the bug. Subsequent PS edits to that PSD/TIFF cause the bug to go away.
(Note that I've eliminated LR from the equation -- all my testing is with Photoshop and Mac Preview, which reads the compatibility layer to display a layered PSD or TIFF. The bug is rendering the compatibility layer incorrectly.)
This thread was started because of what I find in my workflow, I wasn’t trying to report another bug.
My problem is Import Raw into Lightroom. Do a minor edit in Lightroom. Right click image and Edit in Photoshop. Do some edits. save and close file. Return to Lightroom and the image has a rectangle overlay at a different opacity than the rest of the image.
That is what I reported.
If this thread is now to fix a different issue for a different workflow then I’ll leave you all to it.
Right, all the evidence indicates you're tripping over the Photoshop 21 bug with feathered layer masks. It's a Photoshop bug, not a Lightroom bug. If you upload a raw file exhibiting the problem, rather than the edited TIFF, we can confirm that.
When PS saves a multi-layer image in a PSD or TIFF, it creates a hidden compatibility layer that's the composite of all the layers, equivalent to the result of Layer > Flatten Image. LR and other apps (such as Mac Preview) read the compatibility layer to display the image. PS itself doesn't display the compatibility layer -- it just creates it for use by other apps.
When the option Preferences > Performance > Legacy Compositing is off, the bug causes the feathered layer to be incorrectly rendered in the compatibility layer. Thus, the TIFF or PSD looks correct in PS but incorrect in LR and other apps.
When you save the image from PS to a JPEG (or any format that flattens the layers in the image), the bug doesn't occur. Similarly, if you reopen the PSD or TIFF and force it to be resaved, the bug doesn't occur. It only occurs when you open a raw within PS, add a feathered layer, and then save it as a PSD or TIFF.