Note: This update has been re-released on March 23rd to fix an issue in the prior day’s update that caused mouse sensitivity in multiple games to be impacted by opening and closing the overlay.A new Steam client has been released and will be automatically downloaded.General
Added spelling suggestions to Library and Steam Chat context menus
Showing size on disk for DLCs under game properties
Fixed showing localized game names in pop-up notifications
The Steamworks SDK redistributable used by dedicated servers has been brought up-to-date with this release

In-Game Overlay
Improved responsiveness of web based UI and of the friends and chat UI inside the in-game overlay
Fixed overlay support for 32-bit Vulkan applications on Windows

Steam Input
When using Steam Input, active controllers fill in XInput slots in the order they generate input (e.g. the first person to click A will be player 1 in many games
Fixed issues with game detecting controllers while the overlay is up on Windows
Fix issue with analog axes in the Windows version of Slay the Spire

Remote Play
By default stream at 1080p to prevent accidental 4K streams
Added an option to stream up to 8K resolutions (results may vary depending on hardware)
Added a menubar at the top that gives you an easy way to stop streaming
Added a toast when you connect a controller that shows how to bring up additional controller features
Improved audio range when using volume controls

Remote Play Together
Added support to invite anyone to Remote Play Together

Now you can Remote Play Together with anyone – no Steam account needed to join your game with the click of a link. Simply launch any of the thousands of games with support for Remote Play Together, then grab an invite link from your Friends list in the overlay. Send the link to your friend on Windows, macOS, Linux, iOS or Android, and they can click your invite to join in the fun. For more information, and to share your feedback regarding the new Invite Anyone functionality, join us in the Steam Remote Play Group.

Inviting a friend will not auto-start a voice chat session
Remote keyboard and mouse are disabled by default in Remote Play Together
Added a connect dialog that gives you information about who is playing and what input they’re using
Local controllers fill XInput slots first and guest controllers fill slots in order of arrival
Fixed issue with game controllers not being detected properly when the game doesn’t have focus
Fixed bug with controller not being recognized if Xbox Configuration Support was enabled on the client PC
Enabled direct peer to peer connection by default (this can be changed in the Steam Remote Play settings)
Fixed local guide chord input leaking through to the host computer

SteamNetworkingSockets
Fixed bug causing 64-bit Windows games to not attempt a direct connection and always relay using Steam Datagram Relay.
Fixed bug causing GetQuickConnectionStatus to not populate m_cbSentUnackedReliable properly

macOS
Fixed some popup web dialogs that did not close when triggered by the web page to close
Fixed mouse interaction not working with embedded YouTube videos
Fixed overlay not responding to mouse input in certain games on macOS 10.15+
Re-enabled HW acceleration settings on macOS 11.1+

Linux
Added support for the new Mesa single-file shader cache format, reducing disk usage and improving performance when parsing and modifying the cache. (requires Mesa master as of 08101aaaace22)
Fixed a regression where the client would recursively follow symlinks in Proton install folders while discovering music files,,Read More