This morning he got replaced by a screen that you don't have to swipe up to view, and includes both hourly and 10 day forecasts.
I followed some instructions I found elsewhere to clear google search data (settings: apps: google app: storage & cache: Manage space) and that brought the frog back for about 10 minutes. Then the weather line disappeared entirely from At A Glance. I rebooted the phone and got the weather back in the widget, but the frog was gone again.
Would really like him back... is there something else I can try.
ETA 5 days later my froggy friend is back... I hadn't tried changing anything else, it seems just random
Looking closer, technically the frog is there but the picture used to be a full screen size and now he's very small. ETA just for the record I have a Pixel 4a so I'm on 13 and supposedly no longer get system updates.
Interesting. Is more information hidden behind clicks in this screen? I'm missing a lot of detail in the screen, like humidity, wind speed and UV index.
Regarding system updates, I don't think that matters. The weather screen is bundled in the Google-app afaik, which you will continue to get updates for until the app itself breaks compatibility with your OS, which is unlikely to happen this decade, probably.