1st Week number changes date later in year.

I run a calendar every year, and over the last few years, the WEEK numbers change a few months into the year. Throws off weekly numbers for every week. Now the year calendar is now 1 week behind.

I suspect Its the week ending in Sunday format, Sun-Sat calendars show proper week numbers, Mon-Sunday week numbers now mismatch. Week numbers should be the same.

Calendar command = ncal -wMb 2023

Calendar printed in Jan 2023 this year. Notice the Week 1 starts on 2nd.
           2023
         January February March
 w| Mo Tu We Th Fr Sa Su w| Mo Tu We Th Fr Sa Su w| Mo Tu We Th Fr Sa Su
52| 1 5| 1 2 3 4 5 9| 1 2 3 4 5
 1| 2 3 4 5 6 7 8 6| 6 7 8 9 10 11 12 10| 6 7 8 9 10 11 12
 2| 9 10 11 12 13 14 15 7| 13 14 15 16 17 18 19 11| 13 14 15 16 17 18 19
 3| 16 17 18 19 20 21 22 8| 20 21 22 23 24 25 26 12| 20 21 22 23 24 25 26
 4| 23 24 25 26 27 28 29 9| 27 28 13| 27 28 29 30 31
 5| 30 31

Ran Calendar again in April this year, Now the week 1 starts on Sunday 1st.

        January February March
 w| Mo Tu We Th Fr Sa Su w| Mo Tu We Th Fr Sa Su w| Mo Tu We Th Fr Sa Su
 1| 1 6| 1 2 3 4 5 10| 1 2 3 4 5
 2| 2 3 4 5 6 7 8 7| 6 7 8 9 10 11 12 11| 6 7 8 9 10 11 12
 3| 9 10 11 12 13 14 15 8| 13 14 15 16 17 18 19 12| 13 14 15 16 17 18 19
 4| 16 17 18 19 20 21 22 9| 20 21 22 23 24 25 26 13| 20 21 22 23 24 25 26
 5| 23 24 25 26 27 28 29 10| 27 28 14| 27 28 29 30 31
 6| 30 31