Who steered you to using an R-Pi these days? You're going to want something a bit better, especially in the RAM department. Like others mentioned, I would bet it's failing and restarting because R-Pis just aren't going to cut it for a node option anymore. I say this as someone who was using an R-Pi Umbrel as my node for a few years and finally broke down and upgraded to a Start9 last year because of all the issues I was having. If I didn't restart the node every couple days, it would simply stop syncing new blocks. When I first got it, my Umbrel took over a week to sync the chain, and it was a good chunk smaller then (May 2021). When I got my Start9 last year, it synced the chain overnight. RAM makes SO MUCH difference, it's ridiculous.