I have this same problem, but I’m still using an iPhone 6...that will change very soon :) possibly within hours
Cachly has shut down when I switch to another app to grab text, navigate with a map program, check a web page, answer a text, etc
i’ve been experiencing it for about 9mos - year. I have shutdown all apps and also removed all photos, and restarted the phone to free up as much resource as possible
My next solution is new phone, wanted to see if there is any further actons I can take to avoid the occurrence on the new device