You know what it looks like… but what is it called?
TAKE THE QUIZ“upon/on”
The following 2 entries include the term upon/on.
take it upon/on oneself
idiom: to do something that needs to be done even though no one has asked one to do it
upon/on someone's return
idiom: when someone returns or returned —often + from
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Merriam-Webster unabridged