バージョンの末尾の数字が"9"から"10"へと桁が上がっているのですが、以下の文を見るとスモールアップデートと少しの重要なバグ修正ということみたいです。
paint.net 4.2.10 - released on February 13, 2020
This small update fixes a few important bugs, most notably with installations that directly use the MSI file for deployment (e.g. AD/GPO).
Fixed: Installations that directly use the MSI (e.g. AD/GPO deployments) no longer need to run the repair process immediately after installation. Some important DLLs were not being updated because while their assembly version was different, their file version was unchanged, so Windows Installer incorrectly skipped over them. Click here for more information.
Fixed: Loading an image with an enormous photoshop:DocumentAncestors node in the XMP metadata will no longer hang the app
Fixed a rare crash in the auto-updater UI related to font initialization
Improved performance when clicking OK on an effect or adjustment dialog that has already completed part of its rendering
Paint.NET - Free Software for Digital Photo Editing
https://www.getpaint.net/index.html
https://www.getpaint.net/roadmap.html
