Hi Aaron
I'm AnnaThomas and I'd happily help you with your question. In this Forum, we are Microsoft consumers just like yourself no one here is a Microsoft employee.
According to UMAR MAJEED in the thread below, Unfortunately, there is no way to remove the subject line in Teams messaging at this time. This is a new feature that Microsoft has added, and it is not yet possible to disable it.
Reference: https://answers.microsoft.com/thread/05ba271c-8d8e-4e6c-b158-abac43ddc0db
I hope this helps ;-), let me know if this is contrary to what you need, I would still be helpful to answer more of your questions.
Best Regards,
AnnaThomas
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