I deleted all my content but I did it over the span of a few days, to let the different caches around reddit to update with the new void, and my content is still deleted (so far).
I said it before and I say it again: if you have the patience to do so then make sure you overwrite your content with chatgpt generated content, as the future AI that will feed on your post HATE feeding on already AI generated stuff. It makes the AI diverge.
edit: Filling your previous content with random generated content also make it harder to restore because it is harder to spot, compared with the comments which are simply "deleted". Also, if all of it is really true, congratulation to reddit for demonstrating to everyone and specially the USA how useful the GDPR is for the citizen.