Updates to Site Pages thumbnails do not get reflected in search results

[erosu-hab]

Version used
4.8

Describe the bug
After the initial setup of a page, any subsequent updates to the thumbnail do not get reflected in search results.

To Reproduce
Detailed steps to reproduce the behavior:

1. Create a new Site Page, say “News-with-thumbnail.aspx”
2. Set the header to Plain and set the thumbnail to an image of your choice.
3. Publish the page.
4. Create another Site Page, say "Search.aspx"
5. Add the PnP Search results web part.
6. Select the SharePoint as data source.
7. Set query template such that the page created in step 1 gets displayed in the results. For example: Path:https://tenant.sharepoint.com/sites/test/SitePages/News-with-thumbnail.aspx
8. Select the default Cards display template
9. Save and publish Search.aspx
10. News-with-thumbnail.aspx should display the thumbnail set in step 1.
11. Go to News-with-thumbnail.aspx and set the thumbnail to a different image.
12. Publish the page.
13. View Search.aspx page
14. Search results should display the updated thumbnail. Instead, the old thumbnail gets displayed.
15. View the OOTB Microsoft search results page.
16. News-with-thumbnail.aspx shows the correct thumbnail on this page.

Expected behavior
When the thumbnail gets updated for a page, PnP search results displays the newly set thumbnail.

Desktop (please complete the following information):

• Chrome, Edge

Additional context
The PreviewImageUrl slot is mapped to AutoPreviewImageUrl.
To see the updated thumbnails, I needed to either clear the bowser cache, browse incognito or browse in a different browser.

We’d like our users to see the updated thumbnails, rather than stale content.
Regardless if this is something that can or will be fixed in PnP Modern Search in the future, we'd still like to have an interim solution.
Do you have any suggestions on how to overcome this behaviour? We thought of appending last modified time to PreviewImageUrl, in the display template, to force a cache refresh, but we’re not sure if this would be the correct fix.

Thank you!

[erosu-hab]

We switched to using PictureThumbnailURL managed property instead of AutoPreviewImageUrl. PictureThumbnailURL seems to be working as expected.

[wobba]

Added support to prefer PictureThumbnailURL if present in the data