Please note that Google have, during Android 12 Beta, renamed 'At a Glance' to 'Live Space' - so it could be that they're working on fixing it going forward. But in the meantime, I have found Another Widget to be the perfect answer. On some 21:9 screens anyway. Sony presents a greater problem whereas Motorola's One Vision doesn't seem to.
The Motorola Edge+ I am currently using is technically a 19.5:9 screen, so I guess it doesn't comply - although it is different in a sense, because of those 'waterfall' edges, making the 'front' of the phone's screen very much 21:9. And the 'At a Glance' Widget behaves just like it does on the 21:9 screens that I have tried - rendering the Widget 5x2 for icon-space rather than 5x1 - which takes up far too much space and just looks stupid!
Anyway, Another Widget certainly fills the gap here and adds all sorts of functionality that Google's own widget doesn't, apart from the core issue here. The App is free to use, with no limitation on functionality that I could find, and an invitation to contribute to the developer, Tommaso Berlose. Worth £1.59 of anyone's money to support and encourage.
You can make the Widget behave in a whole range of ways, including to start off with, whether or not it's transparent to your wallpaper or not. I have black wallpaper so it's not an issue, but for those who have brighter colours or moving wallpaper, this is a useful addition. You may need to play with size, colour and style of font in that case, but this widget has that covered too!
Then there's layout where you can align the text how you want it to look, add a separator (even the style) and where what fits where! If you want to you can make the whole widget bigger by adding a clock - again, customisable in all sorts of ways. Or have two clocks if you like to include somewhere you might travel to regularly.
Unlike At a Glance, you can control Calendar events popping up in terms of how long they stay and which ones, even which calendars to show from your chosen calendar app as a filter. Then there's weather - a primary part of the At a Glance for me. As you drill down into the Weather options, which again are plentiful including even Icon packs, there is a choice to be made about which provider to use. Some are USA only, so you have to go off and open an account, get a token to use and so forth. I stick to the simple one which needs none of that mucking about and it seems to do as good a job as the Google one as I click through and it ends up at the very same place.
Underneath the date and weather you can have all sorts of other information popping up - all controllable, including next alarm set, battery status, any custom note you might want to add, notifications from apps and even what song is currently playing on your Music App of choice.
There's tons of stuff in here, most of it is customisable, it's a real breath of fresh air after to fairly locked-down Google version - and even if you don't have a 21:9 screen problem to work around, this works beautifully well on other phones with all sorts of screen sizes. Recommended very highly and first brought to my attention by Zac Kew-Denniss when he appeared on our podcast Phones Show Chat with Steve Litchfield.