Just read this and wanted to leave a note here.
https://www.raspberrypi.org/documentation/usage/video/
On the Pi 4, hardware support for MPEG2 and VC-1 codecs has been removed, so we recommend the use of the VLC application, which supports these formats in software. In addition, VLC has hardware support for H264 and the new HEVC codec.
Could that be an indicator for decreasing support for omxplayer in the future?