Via [url=https://list.valvesoftware.com/cgi-bin/mailman/listinfo/hlds]HLDS[/url]:

[quote=Valve]- Fixed the scoreboard not displaying the proper images for Jungle Inferno Campaign Pass owners
- Fixed a Pyro animation bug related to jumping
- Fixed the Spy-cicle not giving the Spy fire immunity
- Fixed the animation for The Second Banana plate
- Fixed a Scout bug where mini-crits were granted to weapons other than The Atomizer while jumping
- Added the Titanium Tank Participant Medal
- Updated the Mann Co. Store to support the new foreign currencies added to Steam
- Updated the localization files

- Updated pl_enclosure_final
- Fixed a buildable area in BLU spawn for stage 1
- Updated materials for foliage props

- Updated plr_bananabay
- The train will now pass at its maximum frequency after both payloads make it up the large hill
- Fixed players getting pushed into the underwater tunnel and ceiling over right spawn exit
- Fixed spawn gates trapping enemy players
- Amplified train engine sound
- Reworked left spawn exit
- Added small barrier near final cap
- Improved performance in some areas
- Reduced push force near outer rocks

- Updated cp_mossrock
- Fixed small area where Engineers could build in initial BLU spawn
- Fixed area where you could fall in the pit and not die
- Fixed cases where you could block the train without dying
- The train now doesn't kill you if your toe touches it
- Optimized FPS around the last point. Should be significantly better.
- Brightened the underside of last point slightly
- Improved clipping around the ramp to last point
- Fixed a case where your view would glitch out on the sign near cap A[/quote]

Rumor has it:

- If you want to take a peek into what was localized, or at some HUD file updates, [url=https://github.com/SteamDatabase/GameTracking-TF2/commit/a5538f33492c8836db173ac57d38dcdebd485734]here they are[/url]

- Size is ~140 MB
- This update was originally supposed to be released yesterday, but was scrubbed after an issue was found