Strange results with text groups with mixed Apple and Android members

I'm in a text group with seven people, four of whom are using an Apple device and three on Android. I know a mixed group like this puts certain limitations on leaving the group and other things. But one thing I'm puzzled about and didn't expect to see is that on all four of my Apple devices--my two iPads, iPhone, and iMac--somehow our single text thread has split itself into two separate threads. I can't quite see how the two threads relate to each other, but some messages from the group end up in one thread and others on the other thread. And the division of messages between the two text groups is different among my four devices! On my iPad, a lot of my own messages end up in one group, but that's not the case on my iMac.

In short, I can't figure out how or why Messages splits this group text thread into two, and I certainly can't figure out how it determines which text to put into which thread.

Has anyone else seen this behavior?

(I'm putting this message into the MacOS section, but it's equally applicable to iPadOS and iOS.)