Long delay in receiving some messages

Yesterday morning I received a series of messages (some personal, others of account validation) that were 36 hours old, while during this time I continued to exchange without any particular problem.

Likewise today, in the middle of an important conversation, I stopped receiving messages, I tried an online service to send an SMS to my number and I didn’t receive it. After restarting the phone, the online service works but I still haven’t received the messages from earlier.
I can’t afford to wait several days waiting.

How to what messages I haven’t received yet and how to prevent it from happening again?

Note. I was under iOS 14 Beta 4, I deleted the developer profile to see if I could go back to iOS 13 but now it just says "iOS 14.0, your software is up to date".