Photos not detecting RAW & JPEG duplicates

If they're different file formats then they're not duplicates, for a start the jpeg will be a lot smaller (in MB/kb) than the Raw. And because you did the export as jpeg there is no longer a connection to the Raw. The raw was created by your camera, these jpegs were created by the app you exported from. So that link is severed.

All is not lost though. You could isolate the relevant images in a Smart Album:

File -> New Smart Album

Photo -> Is not. -> Raw

and then add conditions for the date, for instance: Between Jan 1 2020 to Dec 31 2020 and so on.

Once isolated they can be deleted easily.

The duplicate detection is different on Import from the Duplicate detection after import.

When we are importing image files, Photos ich checking for exact duplicates.

But later it will be scanning for similar photos. Only then it will discover different versions of the same photo in different file formats, different resolution, or different adjustments.

The duplicate check after import will take a very long time, as Photos has to compare what the photo is showing, not just the file attributes. If your library is large, you may have to wait for several weeks, before the first duplicates will appear in the duplicates album. The duplicates album is available in macOS 13 Ventura or later: Remove duplicate photos in Photos on Mac – Apple Support (UK)

As far as I know, the duplicate detection in Photos should be able to recognize duplicate photos in different formats. A third-party app called Cisdem Duplicate Finder may also be helpful. It can find identical photos in different formats or sizes and allows you to set similarity thresholds for comparing photos. Note that it's a paid app. But it lets you find and view duplicates for free.