Synapse 1.19.1 is a bug fix release to fix two bugs introduced in 1.19.0.
Those two bugs were related to the new rate-limiter on room joins, which was introduced in 1.19.0.
The first bug caused Synapse to ignore exceptions to rate-limiting for application services.
The second one prevented profile updates from being correctly propagated across rooms.
Sorry if you have been bitten!
Get 1.19.1 from github or any of the sources mentioned at https://github.com/matrix-org/synapse/blob/master/INSTALL.md.
Changelog since v1.19.0
No significant changes.