I had n41 all the time and now in morning its n71 until Nokia is rebooted

Just a quick thought… have the trees recently sprouted leaves ?  I.e. Trees/Leaves between your device and the tower ?  I've noticed since build (Jan/Feb), service on n41 has switched more often to n71 indoors.   Higher frequencies are more prone loss than lower.  There are ~4 trees between me and the tower, and performance on n41 has dropped a bit on the device.  It isn't nearly as noticeable on my S21, as it also has n25, and isn't stationary.  Easiest way for me to notice …. upload goes up from ~30 Mbps to +60Mbps.  Download goes from ~400-450 down to 250-300.   Still works well for $25/month