Hi, same problem here. I attach the error message for completeness.
I will also try to remove and reinstall everything during the weekend.
Mailspring Version: 1.10.8-8ea2a61f
Platform: linux
Account State: sync_error
Account Provider: gmail
IMAP Server: imap.gmail.com
SMTP Server: smtp.gmail.com
--------------------------------------------
**...warning messages about private emails...**
9970 [2023-03-28 09:30:16.077] [background] [info] syncFolderUIDRange for [Gmail]/Tutti i messaggi, UIDs: 194419 - 196072, Heavy: false
9970 [2023-03-28 09:30:16.276] [foreground] [info] [local-42ee1479-3d93] Running EventRSVPTask performRemote:
9970 [2023-03-28 09:30:16.277] [foreground] [critical]
***
*** Mailspring Sync
*** A JSON exception occurred during program execution:
*** [json.exception.type_error.302] type must be string, but is null
***
10020 [2023-03-28 09:30:16.844] [main] [info] Identity created at 1644062718 - using ID Schema 1
10020 [2023-03-28 09:30:16.845] [main] [info] ------------- Starting Sync (MYEMAIL@gmail.com) ---------------
10020 [2023-03-28 09:30:16.852] [metadata] [info] Metadata delta stream starting...
10020 [2023-03-28 09:30:18.849] [background] [info] Fetching XOAuth2 access token (gmail) for 308ff103
10020 [2023-03-28 09:30:18.953] [background] [info] Marking all folders as `busy`
10020 [2023-03-28 09:30:18.954] [background] [info] Syncing folder list...
10020 [2023-03-28 09:30:20.623] [background] [info] Syncing folder list...
10020 [2023-03-28 09:30:21.001] [background] [info] syncFolderUIDRange for [Gmail]/Tutti i messaggi, UIDs: 196067 - 196072, Heavy: true
10020 [2023-03-28 09:30:21.368] [background] [info] - [Gmail]/Tutti i messaggi: remote=4, local=4, remoteUID=mH7CJgpnLchqUC6uNEorzrD8JoKGBDWqZjQJ3aw2
**...warning messages about private emails...**
10020 [2023-03-28 09:30:22.015] [background] [info] syncFolderUIDRange for [Gmail]/Tutti i messaggi, UIDs: 194419 - 196072, Heavy: false
10020 [2023-03-28 09:30:22.183] [foreground] [info] [local-42ee1479-3d93] Running EventRSVPTask performRemote:
10020 [2023-03-28 09:30:22.183] [foreground] [critical]
***
*** Mailspring Sync
*** A JSON exception occurred during program execution:
*** [json.exception.type_error.302] type must be string, but is null
***