Merriam-Webster says that the pronunciation of "serious" or "series" is
ˈsir-ē-əs
https://www.merriam-webster.com/dictionary/serious
But I do not make the si sound ("sin"), I made the sē sound ("see") in the first syllable. My pronunciation is ˈsēr-ē-əs (see-ri-ous).
In the word "seer" Merriam Webster allows 2 pronounciations, one of which is sē,
ˈsir & ˈsē-ər
but it doesn't do that for "serious" or "series." So is my pronunciation incorrect? I'm in the USA.