Regarding Vishay BPW21 photodiode, it may have suffixes like below:
See product manager response regarding the meaning:
"The V27 must be fro an older batch if I am reading correctly V= vishay 2= 2012 7= July
Now I believe the first digit is the year and the last two are the week so the 1=2021 and week is 35th week."
BPW 21 E9272