I had this 1-2 years ago on an FP3, triggered by the modem driver crashing when being subscribed to particular mobile towers / radio tech. better to have someone with a FP4 respond, but I’d guess this is similarly a driver crashing. An indicator this being the modem is when it happens outside your house and has a location aspect
Luckily I’ve never experienced this on my /e/OS FP4. But there are similar reports for FP4 with FPOS (stock OS). Often a helpful workaround was to disable 5G. I think it’s at least worth a try.