Even direct from TI's own store, there are still varying levels of available.
1. In stock
2. In stock - you can actually buy (more on that later)
3. Future Inventory - More units week of day month 2022
4. Future Inventory - More units week of day month 2022 - you can actually buy (more on that later)
5. Out of stock
6. Out of stock - replaced by newer part
7. Out of stock - replaced by newer part which is also out of stock!
So what's this "you can actually buy" stuff about then?
Firstly the website can be 20 minutes behind the actual warehouse stock.
Then you have to be an actual company to buy some parts (no free gmail/hotmail accounts).
Then you have to not be using anything that might block all their 3rd party tracking, popup notifications, captchas, cookies

Some parts are more strict on who can buy them, dunno why.
Finally TI have multiple warehouses around the world, and try to ship from the nominal one for your country, if the parts you want are in multiple warehouses you can buy some but not others.
It's all a huge pain, took me hours to figure out how to get one order to go thru.
You can add parts to your cart, but then have the site demand you remove them at checkout as they cannot be fulfilled (but still be in stock the next day!).
The "More units week of" thing is them drip feeding parts into the market, say 500 this week (who knows when), another 500 the week after, etc.
Of course this is not obvious, so if you don't happen see the stock appear that week, then it seems like the expected date keeps slipping.