Set a bandwith limit is a prior post from you wanting one. Did you limit at any time of backup history? If so:
Upload throttle corrupts backup, especially OneDrive. Analyzed, with code proposed. #3787
Google Drive was not tried by me because the fixed-and-tested fix is so simple it seemed easier to just do however (to my dismay) nobody has shown interest in the issue. Meanwhile I’m unsure how common it is.
I’m not certain this is what you hit. Your failure is seemingly on the download verification of a sample set of remote volumes done after backup itself completes. Is that when you see it? Then the question is whether corruption took place on upload, download, or (seems unlikely) at Google. Viewing About --> Show log --> Live --> Retry should let you see the remote filename that became the Temp file with an unexpected hash.