[BlackjackCF]

I’m likely wrong here but isn’t that a problem with SMS and not necessarily iMessage?

[daedalus_j]

I can exchange MMS to other Android users (and it's MMS, not RCS) that aren't ridiculously compressed, so I've always assumed it was Apple.

[giantrobot]

MMS limitations stem from the carrier. They have different attachment size limits which affects how Messages will encode the content.