Photoshop 28.0.1 opens Cinema 4D TIFFs in Camera Raw despite TIFF handling being disabled — adding ExtraSamples=2 prevents it

I’m reporting a reproducible issue in Photoshop 28.0.1 involving TIFF files exported from Cinema 4D.

Expected behavior:
TIFF files should open directly in Photoshop when TIFF handling is disabled in Camera Raw preferences.

Actual behavior:
Affected Cinema 4D TIFFs unexpectedly open in Camera Raw despite TIFF handling being disabled. I have reproduced this in Photoshop 28.0 and 28.0.1. The same files do not trigger this behavior in an older Photoshop version.

Tests performed:

• Resaving the affected document in Photoshop: the issue persists.

• Copying the image into a new Photoshop document: the issue disappears.

• Deleting the alpha channel: the issue disappears.

• Adding only ExtraSamples=2 (unassociated alpha), while retaining all four channels: the issue disappears.

• Removing only the Photoshop alpha-channel name resources (IDs 1006 and 1045): the issue persists.

Technical findings:
The affected original TIFF has these properties:

• Dimensions: 2560 × 3840

• PhotometricInterpretation: RGB

• BitsPerSample: 8, 8, 8, 8

• SamplesPerPixel: 4

• ExtraSamples tag (338): absent

• Fourth channel: all pixel values are 255

• Compression: PackBits

• No XMP metadata

For the ExtraSamples test, the original compressed pixel data, ICC profile, and Photoshop image resources were preserved. The only tag-level change was adding ExtraSamples=2. The decoded four-channel pixel values were verified to be identical to the original.

The test file uses a replacement IFD appended to the file. The alpha-name resource removal test uses the same IFD replacement method but still triggers Camera Raw, which helps distinguish the tag change from the IFD relocation.

These results suggest that handling a fourth channel without an ExtraSamples declaration may be involved in the unexpected Camera Raw routing. The internal cause is not confirmed, but the difference between older and newer Photoshop versions suggests a regression.

A potentially related investigation was acknowledged by an Adobe Community Manager here:
https://community.adobe.com/bug-reports-557/image-processor-freezes-forces-acr-interface-on-stitched-tiff-files-after-recent-update-1639493

The test images contain confidential content, so no image files are attached to this public report. If sample files are required, please advise whether Adobe provides a secure, non-public submission channel.

Could the Photoshop/Camera Raw engineering team investigate whether a missing ExtraSamples declaration can trigger this behavior, and whether this case is covered by the existing TIFF-routing investigation?