MPEG-TS is used to contain h264 chunks for HLS. MPEG-DASH and the new CMAF standard use fMP4 containers instead. My personal take is that Media over QUIC (MoQ) should support both.

HLS also supports fMP4 now and no one is making new services that use TS (there are some old ones still around with too much friction to switch)

The nice thing about fMP4 is that it's supported by both HLS and MPEG-DASH, so you can save yourself the effort of duplicating all data at the CDN level (or using a CDN that can just-in-time assemble fMP4 and M2TS files from the same underlying source).