Ipad (M5) iMessages not being delivered

Some of the messages on my iPad (M5) show as not being delivered, with a red exclamation mark inside a circle and not delivered underneath. But when I look on my iPhone (16), the messages show as being delivered. This only happens with phones that are not iPhones. I’ve done every fix I could find online, from rebooting to re-syncing and nothing is working. It started a week or so ago. Has anyone else had this issue & if so, how did you fix it?