"The macOS Catalina 10.15.3 update improves the stability, reliability, and security of your Mac, and is recommended for all users.

This update:
- Optimizes gamma handling of low gray levels on Pro Display XDR for SDR workflows when using macOS.
- Improves multi-stream video editing performance for HEVC and H.264 encoded 4K video on the 16-inch MacBook Pro (2019)."

(FYI: the owner that reported poor 2019 Mac Pro Final Cut Pro X performance with 10.15.2 said the macOS 10.15.3 update seems to have solved it.)

Also released are Security Update 2020-001 Mojave, & Security Update 2020-001 High Sierra (downloads below). Here's the article on security fixes in macOS 10.15.3 and Security Updates 2020-001 for 10.14.6/10.13.6. (See below for info on Safari 13.0.5, included in macOS 10.15.3, available for macOS 10.14.6/10.13.6.)

macOS 10.15.3 Delta & Combo Update Downloads
• Download macOS Catalina 10.15.3 Update ( 2.99 GB)
• Download macOS Catalina 10.15.3 Combo Update (4.59 GB)
  
  Security Update 2020-001 Downloads
  
• Download Security Update 2020-001 (Mojave) (1.62 GB)
• Download Security Update 2020-001 (High Sierra) ( 1.92 GB)

• Safari 13.0.5 includes security fixes, available for macOS 10.14.6 and macOS 10.13.6.
  (Safari update is included in macOS 10.15.3.)
  
  
• iOS 13.3.1 release notes (17D50).
• iPadOS 13.3.1 release notes (17D50).
  
• About the security content of iOS 13.3.1 and iPadOS 13.3.1.
  
  
• iOS 12.4.5 release notes (16G161).
  - "provides important security updates and is recommended for all users."
  (Security Updates page notes "This update has no published CVE entries".)
  
  
• tvOS 13.3.1 release notes (17K795) and security fixes.
  - This update includes general performance and stability improvements. (the usual note.)
  
  
• watchOS 6.1.2 release notes (17S796) and security fixes.

"Installation Note: The installer requires System Preferences to be launched during the installation process. Do not manually close System Preferences until after clicking Allow in the Security & Privacy Preferences, later in the process.

The installer also requires rebooting the system after the installation process. Do not launch any other applications until the process is complete and the system has been rebooted.

New in Release 387.10.10.10.40.134"
(No new info, same notes on D/L page as previous drivers, so I won't repeat it here.)

• Apple Reports Record First Quarter Results (press release)
  
  
• Apple delivers a new redesigned Maps for all users in the United States (pr)
  
  
• Company of Heroes comes to iPad on 13 February (feral interactive)

• How to clean your Apple Pro Display XDR
  
  
• Mac Pro (2019) status indicator light behavior
  
  
• How to Set up and use iCloud Photos
  
  
• How to Find audio-described content in the Apple TV app or iTunes Store
  
  
• How to Authorize or deauthorize your computer for iTunes Store purchases
  
  
• If you can't stream or watch movies or TV shows from the Apple TV app, iTunes Store, or third-party apps
  
  
• How to Buy movies and TV shows from the Apple TV app
  (was titled "Download or stream movies and TV shows from the iTunes Store.")
  
  
• If music, movies, or TV shows from the iTunes Store, Apple Music app, or Apple TV app stop downloading
  
  
• If you can't connect to the App Store, iTunes Store, or other Apple services
  
  
• How to Find audio-described content in the Apple TV app or iTunes Store
  
  
• Resolve USB-related alerts in iTunes
  
  
• If you see an error in Finder or iTunes on your computer
  
  
• How to take a screenshot on your Mac
  
  
• Read books and more with Apple Books (app)
  
  
• What's new in the updates for macOS Catalina (added 10.15.3 info)
  
  
• How to Reset the System Management Controller (SMC) of your Mac
  
  
• How to Sync your iPhone, iPad, or iPod using your computer
  
  
• If you can't download or update apps on your iPhone or other Apple device
  
  
• Institutions that support health records on iPhone and iPod touch

• About the security content of iCloud for Windows 10.9.2 (Apple)
  
  
• About the security content of iTunes 12.10.4 for Windows (Apple)