GrapheneOS
Unfortunately, whatever you are referring to regarding the security preview release, has broken something in mms for secondary users. I'm not alone in this. In my case, outgoing messages in group messaging fails. One-to-one messaging works.
The issue initially was, any out going text that included an emoji or other image failed to send from both owner and secondary. Image free messages were not affected, delivered normally. After multiple reboots and a network reset, messaging from the owner profile returned to normal, ditto one-to-one messages from the secondary. However, now ALL attempts to respond to group texts in the secondary, including image-free texts, fail. Incoming texts from group members arrive just fine, including images.
Never had this happen before. I've been using the same app on GOS for more than a year.
I'm using Textra, and reverted to stock GOS mms for testing, then installed Quik sms for another test. The problem is consistent across all three apps.