@fastfinge In thunderbird there is, but I don't gthink there's much with Element, but if you're using a element X compatible server maybe you need it. I'm not an expert on the changes there. I'm still confused on which matrix server is the best one. Looks like there are two of them being maintained: An official one and unofficial.
@serrebi There are a bunch. I'm using Conduwuit, and it fully supports sliding sync. Conduwuit isn't associated with the VC funded Matrix organization and there commercial/paid offerings.
