945 Sleep Tracking went to crap in June

I checked my sleep data for 6 months back and I don't see any changes.

Have you checked the movement for your sleep? Since you says it misses the start of you sleep then check the movement just before the watch logs sleep. Use the web and click the movement button: https://connect.garmin.com/modern/sleep/2021-10-08 

But I do nothing different than I did before the update. Also, since the update, I never see sleep in the Garmin app on my phone until way late in the day. I can sync till the sun goes down but it doesn't appear until it wants to late in the day.

Check the sleep widget on the watch. When you do that a sync will happen and you will get the sleep into Connect.

I have no idea. Maybe you needed to do that before but you looked at the widget some time before you checked in the app. You just have to press up or down to open all the widgets. You don't have to click on the sleep widget. It doesn't even have to be visible on the watch.

When I did some tests it synced if the sleep widget was just off screen which in my widgets will be if I press down button because it is the 3rd widget from the top. If I press up button it will be too far off screen to initiate a sync.

Sadly,no. I always used to wake, grab my phone and sync and as soon as sync was done, my sleep details would appear and bbefore I ever got out of bed I was looking at my stats. As soon as that update happened, that stopped and the sleep score went from fluctuating between roughly 50 (after night of few beers) to 90's on good nights. Now the score varies from 2ish to 34 is the highest I've seen. 

thanks for your help, btw.

Have you tried that solution which helps sometimes, to hold the On/Light-button pressed for 15 seconds to turn off the watch? And then do a restart. Helps all sorts of mysterious problems - occasionally.

Well, sleep tracking when we got the Firstbeat algorithm got somewhat usable. The Garmin one gave huge overestimations. Since then it has just been working much better.