fakt/sprawa drugorzędna/bez większego znaczenia/mniejszej wagi

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Note added at 23 hrs (2022-03-04 10:29:54 GMT)
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Footnote - an event, subject, or detail that is not important:
His tumultuous triumph five years ago now seems like little more than a footnote in history.
https://dictionary.cambridge.org/dictionary/english/footnote

3.
If you describe an event as a footnote, you mean that it is fairly unimportant although it will probably be remembered.
I'm afraid that his name will now become a footnote in history.
https://www.collinsdictionary.com/dictionary/english/footnot...