Save Metadata To File sometimes writes huge .acr sidecars for JPEGs unnecessarily

Save Metadata To File will unnecessarily write a huge .acr sidecar for a JPEG that’s been exported from LR and reimported. This affects users who regularly export with the Add To Catalog option. See here for a motivating use case:

https://www.lightroomqueen.com/community/threads/exported-jpgs-with-an-acr-file.54565/

To reproduce  on LR 15.2.1 / Mac OS 26.2:

1. Download and open the attached catalog, which contains a single raw, DSC08981.ARW, with Denoise applied.

2. Ensure the option Catalog Settings > Metadata > Include Develop Settings In Metadata is enabled (the default).

3. Select the raw and export it as a JPEG to the desktop, with Quality = 70 and the option Metadata > Include: All Metadata.

4. Import the exported JPEG with the Add Option.

5. Select the JPEG and do Metadata > Save Metadata To File. Observe that DSC08981.acr is created, about 10.3 MB (three times the size of the .jpg) (incorrect).

6. Delete DSC08981.acr from the desktop.

7. Edit DSC0891.jpg in Develop and change Exposure = -2.

8. Do Metadata > Save Metadata To File.  Observe that no .acr sidecar is created (correct).

9. Delete DSC08981.jpg from the desktop.

10. Select the raw and export it with Export With Previous.

11. Create a new catalog and import DSC08981.jpg from the desktop with the Add option.

12. Select the imported .jpg and do Metadata > Save Metadata To File.  Observe that no .acr sidecar is created (correct).

* * * 

In step 5, Save Metadata To File is incorrectly ignoring the develop setting xmp:AlreadyApplied = True and writing the .acr sidecar even though the contained Denoise result can never be used with the JPEG.  

The inconsistency in results between steps 5, 8, and 12 further reinforce there is no coherent design rationale or use cases for writing a .acr sidecar when xmp:AlreadyApplied = True.