Message history won’t be fully fixed. It can’t be without storing message backups in some cloud somewhere (whether it’s to iCloud, Google Drive, Dropbox, or Signal’s servers) and Signal omits its message history from system backups on iOS and Android.

iOS users are completely incapable of backing up their message history in the event of their phone being lost, stolen, or broken. This omission isn’t justified in any way, as far as I’m aware; I don’t know of any technical reason why following the exact same process as on Android wouldn’t work.

Android users are able to back up locally via Signal, but that isn’t on by default, can’t be automated, needs to be backed up separately, requires you to record a 30 digit code to decrypt it, and has limitations on when it can be used for a restore (can’t restore on iOS, for example). See https://support.signal.org/hc/en-us/articles/360007059752-Backup-and-Restore-Messages for more details.

Message history on linked devices - meaning iPads and desktop computers - is being improved, but it still won’t mean that a user who loses or trades in their phone as they get a new phone will be able to simply restore their phone from a system backup and restore their Signal message history. And even that isn’t anywhere near as easy as on Telegram, where a user can just log in with their password and restore their message history, no backup needed.

It’s great that they’re improving the experience for linked devices, but right now that doesn’t actually help if you lose, break, or trade in your phone. Maybe they’ll later allow users to restore to a phone from a linked device or support backups on iPhones, but right now the situation with message history isn’t just an unfriendly UX, but one that is explicitly and intentionally unreliable for a huge portion of Signal’s user-base.