Since there's a new channel on MYTV DTT now (Awesome TV), I did a bitrate check again...
Video bitrate check on Mux 1 and Mux 2 (as of 28 July 2020)

Audio bitrate check on Mux 1 and Mux 2 (as of 28 July 2020)

Radio channels on Mux 2 (as of 28 July 2020):

Note: Only Video tracks (VPID) and Audio tracks (APID) are shown above. Other data (e.g. EPG, DVB subtitles, EIT, etc.) are filtered/hidden from view for easier viewing.
Conclusion: Video and audio bitrate remains unchanged... 2Mbps per SD channel
3.5Mbps per HD channel from RTM (TV1, TV2, RTM Sports,...)
4Mbps per HD channel for other TV stations (Media Prima, Al Hijrah, Go Shop, Awesome TV,...)
32kbps HE-AAC v2 audio for any TV channels except from RTM
48kbps HE-AAC v2 audio for RTM channels
112kbps HE-AAC v2 audio for radio channels
Each MYTV's 256QAM mux has a total bandwidth of 34Mbps.
Total used bandwidth (including all other datas like EIT, EPG, DVB subtitles,...) are now 25.9Mbps for both Mux 1 and Mux 2 respectively.
Which it seems to me that if they add another 1 or 2 HD channels on their existing muxes, then their bandwidth is pretty much full already, and we might see Mux 3 to up on air by then, and that's if there's new TV stations willing to
seriously start investing on them.