You can download old IrfanView versions from these sites:
Oldapps.com or Oldversion.com
There were numerous changes, here are only the more important things.
Version 4.57 ( - CURRENT VERSION - )
(Release date: 2021-01-13)
- Improved option "Try registry changes" (Properties->Extensions)
- Option to use new Windows File-Open dialog (Properties->Misc)
- Option to create only Shortcuts (LNK file) in File-Copy dialog
- New Camera RAW PlugIn (based on LibRAW, thanks to Alex Tutubalin)
- Support for WPG format (PlugIn, WPG version 1; thanks to Flurmy)
- Improved GIF reading
- PCX loading bug fixed (thanks to @DmitriyMelikov, CVE-2020-35133)
- MNG PlugIn loading bug fixed (thanks to ThanhTP)
- PCX format moved to FORMATS PlugIn
- Several PlugIns are changed/updated, please install the newest versions:
https://www.irfanview.com/plugins.htm
[
Older versions - History]