MIXO does not currently appear to have an option to display the release date for tracks in your library - either as a column in the library view or the track info view. I use this feature in Rekordbox a lot and I'd love to see it in MIXO as well - both for reading and writing that tag.

The actual ID3v2.4 frame is called TDRL - "Release Time" - and the specification (https://github.com/id3/ID3v2.4/blob/master/id3v2.4.0-frames.txt) defines it as such:

TDRL
The 'Release time' frame contains a timestamp describing when the audio was first released. Timestamp format is described in the ID3v2 structure document [ID3v2-strct].

This tag is supported by a multitude of other ID3v2-aware applications, including Rekordbox and Mp3Tag, as well as at the OS level in Windows and MacOS, so it'd be really awesome to have in MIXO as well.