The original Wordle came with a pre-baked ordered list of 2315 "secret" words, off which the daily secret word was looked up (I think based on local time). The list was right there in the javascript code of the game (alongside the list of 12972 allowed guess words). It covered dates from 2021-06-19 to 2027-10-20.
Then in January 2022, the NYT bought Wordle, and started tweaking both lists, first shrinking the secret word list to 2309 entries, but leaving the logic otherwise intact. Fast forward to today, I looked up the current code [1], and it seems that there are now 14855 allowed words. The first 12546 are ordered alphabetically (0: "aahed", 12545: "zymic"), and the next 2309 are not. This may suggest that the latter are the secret words, but the logic for picking them has changed: I found no obvious sequence, when compared to the last few days' secret words. So it's either a more complex sequence, or the secret word is picked server-side.
In any case, I guess they decided to re-shuffle the list now at day 1689 / 2309 in order to avoid giving particularly assiduous player an additional bit of information: they can exclude all previous secret words. (To be accurate, I think this would be 1.897 bits, but my information theory is rusty.)
Then in January 2022, the NYT bought Wordle, and started tweaking both lists, first shrinking the secret word list to 2309 entries, but leaving the logic otherwise intact. Fast forward to today, I looked up the current code [1], and it seems that there are now 14855 allowed words. The first 12546 are ordered alphabetically (0: "aahed", 12545: "zymic"), and the next 2309 are not. This may suggest that the latter are the secret words, but the logic for picking them has changed: I found no obvious sequence, when compared to the last few days' secret words. So it's either a more complex sequence, or the secret word is picked server-side.
In any case, I guess they decided to re-shuffle the list now at day 1689 / 2309 in order to avoid giving particularly assiduous player an additional bit of information: they can exclude all previous secret words. (To be accurate, I think this would be 1.897 bits, but my information theory is rusty.)
[1] https://www.nytimes.com/games-assets/v2/9003.896ec900f2a1ce8...