I have a Samsung Note 8 and the wife has a Samsung Note 9. Both device's cellular signal tanked after we upgraded our personal account's plan to unlimited.

On our previous data plan the call quality and mobile data bandwidth was great, however nearly ever call since has been completely terrible and the data is even worse.

If I was in a terrible accident and called 911 for assistance, I would die as they would think it was a prank call from an autotuned robot.