Likely the version of the main tweak or the installer script used to build the IPA.
Short for YouTube UHD, this enables 1440p (2K) and 2160p (4K) video resolutions on iOS devices that don't natively support those codecs. 2.2.3_YTK _DEMC_AB_iSB_RYD_YouMute_YTUHD_18.09....
If you see a "Something went wrong" error on version 18.09, you may need to go into Settings > YTUHD and enable "Fix playback issues" . Likely the version of the main tweak or