The deinterlacing section on the 4K / HDR page of the wiki says that for interlaced content Kodi will not do the proper rate doubling without removing the original frame rate from the whitelist.
I think this may be outdated and no longer correct?
I am playing 480i29.97 content today and the output is 1080 @ 59.94, even though 1080 @ 29.97 is still in the whitelist.