“When you use Signal, your data is stored in encrypted form on your devices. The only information that is stored on the Signal servers for each account is the phone number you registered with, the date and time you joined the service, and the date you last logged on.”
Yeah this same thing happened to me. I rarely get messages in signal anymore and can’t reliably know who still has it installed. It’s great for folks you are in regular communication with though.
I made it easy by making it the only messenger I use. Sure, you can send me a sms, but that’s not gonna work for pictures and especially videos.