In my experience, you can’t have too many options when it comes to dealing with gradients. If you’re not aware, Cyril Richard has added a new script to Siril called Auto Gradient Removal. It works very well and can deal with complex as well as simple gradients.
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If you have a pesky gradient that’s been resistant to the usual methods I would highly recommend that you give it a try. One note, like most gradient removal tools it likes clean edges so be sure and deal with that first.