Not too many suggestions so far so my 2 euros worth
PixLab has a point about how representative the clip is, what works here might give different results for a whole image. However (always a however)
A look at the clip properties and the jpeg quality is very low, 20 This might just be the clip and the original might be OK.
Jpeg quality settings are not linear. There is a big file size saving for very little loss in quality 95 down to about 80 but 50 and below the other way round, big loss in quality for very little reduction in file size.
The file resolution is 2400x2400 pixels-per-inch (ppi) This from a scan setting ? Photo quality generally taken as 300 ppi, no great benefit in scanning over 600 ppi. It is up to you.
What linux are you using, and what 'flavour' of Gimp - from repository / flatpack / snap / PPA /
appimage (edit 2.10.28 not appimage) ? It will make a difference when it comes to available 3rd party plugins.
Using the gimp_gmic_qt plugin see:
http://www.gmic.eu and a 3 minute video on how I might proceed
https://youtu.be/jKcWyFCz4Mg