Is there a quick way to “flatten” an image in iOS

I use the ‘markup’ extension in iOS Photos to ‘black out’ sensitive information in screenshots, occasionally. Unfortunately, this leaves the “revert” button, meaning that said sensitive information is sitting archived in my iCloud Photos indefinitely. I've got the messy solution of texting myself the modified image, deleting the original, deleting it *again* from Recently Deleted Photos, and then re-saving it from the text-message I sent myself … but that's no fun. What's the quickest way to turn a modified photo into a flattened copy of itself?