In ID3v2.4, the year and date are written into the same frame, "TDRC", which also supports times, meant to be formatted as yyyy-MM-ddTHH:mm:ss (with varying levels of specificity).
In ID3v2.3, the year and date are written to separate frames, "TYER" formatted as yyyy, and "TDAT" formatted as DDMM.
I have ID3v2.4 selected for MP3 files, and my interest is to read and write in only this standard.
Musicbee seems to write to BOTH tag standards when ID3v2.4 is selected, writing a TDRC and TYER tag when a year is entered, as well as a TDAT frame when a further date is entered.
I believe this is likely an erroneous behavior, Musicbee seems to read just fine from only TDRC. It should not be writing the TYER and TDAT frames when ID3v2.4 is selected, as these frames are not a part of the spec.
On a further note, use of the tag inspector seemed to not be able to remove the TYER and TDAT frames on their own in version 3.3, this isn't the case on the latest beta.
References:
https://id3.org/id3v2.4.0-frameshttps://id3.org/id3v2.4.0-structurehttps://id3.org/d3v2.3.0