When I subscribe to https://stackexchange.com/feeds/questions using feedly.com I sometimes see questions more than once in my feed. I suspect this is because when questions titles are changed the target URL also changes.
For example, my feedly feed shows two entries for question 59167 with slightly different id values:
https://politics.stackexchange.com/questions/59167/why-are-masks-a-political-topic-in-the-ushttps://politics.stackexchange.com/questions/59167/why-are-mask-mandates-a-political-topic-in-the-us
I'm not an expert on rss/atom feeds but I suspect the problem is that the entry's id field is expected to be unique and permanent.
id --
Identifies the entry using a universally unique and permanent URI. Suggestions on how to make a good id can be found here. Two entries in a feed can have the same value for id if they represent the same entry at different points in time.
I'd humbly suggest using the permalink for the id or even a non-URL URI that just uses the question's numeric ID that never changes. Perhaps even better would be to follow the advice for generating the atom id on https://web.archive.org/web/20081225232147/http://diveintomark.org/archives/2004/05/28/howto-atom-id which would end up with something like tag:politics.stackexchange.com,2020-10-20:/q/59167
