Dangerous to Backup with Time Machine if external drive has file structure issues?

I have a partitioned external drive that I've been using since 2019. Occasionally and recently I've been experiencing issues with mounting/unmounting the volumes. I'm unable to carry out first aid through Disk Utility for one of the volumes, getting the "File system verify or repair failed. : (-69845)" error. I've been regularly backing up the drive to another external Time Machine drive. Given recent erratic behaviour on my partitioned ExHD, my instinct is to back it up as I normally would. I will very shortly be buying a replacement, and will use Time Machine to transfer the my old drive's content. But then I worry, if this drive has problems that are affecting its ability to mount, etc., will backing up with Time Machine result in these same problems being copied when I get a new drive and transfer the old content via Time Machine? Or does it not work like that? (i'm on Catalina 10.15.7)