You've never noticed that? Here's the one I had in mind, the one that means assumed or believed:
"Supposed [ suh-pohzd, -poh-zid ]
1: assumed as true, regardless of fact; hypothetical: a supposed case.
2: accepted or believed as true, without positive knowledge: the supposed site of an ancient temple."
https://www.dictionary.com/browse/supposed That one is commonly used in legal EN: the supposed evidence, supposed beneficiary (
https://dictionary.law.com/Default.aspx?selected=861), etc. You don't hear it much in everyday spoken EN.
And then there's "supposed to" (required/expected to), for which that dictionary provides no phonetic transcription, but if you've heard Americans say it, you know that unlike the first entry above (in which we say the second S as a Z), for this meaning most of us say it as an S:
"supposed to
1: Intended to; also, believed to, expected to. For example, This pill is supposed to relieve your pain, or You're supposed to be my partner.
2: Required to, as in He is supposed to call home."
https://www.dictionary.com/browse/supposed-to?s=t