GIMP 2.99.19 - Levels to Curves transition makes two nde filters of both of them.

Environment/Versions

• GIMP version: GIMP 2.99.19
• Package: source build
• Operating System: Fedora 39 Linux

Description of the bug

The Levels filter in the color menu has the option to edit settings as Curves, which transition it to the Curves filter. If done in one succession without closing to apply curves it works just fine. However... If the user applies levels, closes levels, then transitions it to Curves the filters will duplicate applying its effect twice NDE. Once again if its done without closing things inbetween are fine.

Reproduction

Is the bug reproducible? Always

Reproduction steps:

1. Apply Color>Levels on the image NDE and give it some light tweak
2. Close Color>Levels
3. Re-edit Levels and "Edit these settings as Curves"
4. Curves is applied NDE duplicating the effect. You will see curves and levels as independent NDE filters.

…

Expected result: Curves transitions to levels successfully Actual result: Two independent filters duplicating the effect

Additional information

Fun fact, I thought of this being a bug, inspiring me to test Levels to Curves transition and then finding it indeed was.This bug was likely in 2.99.18 as well. I think the only way to solve it is to remove the ability to convert Levels to Curves. If any other filters do that transition thing (which I don't think they do) they as well should be investigated for this same bug.