Mojave: TimeMachine never ends, keeps growing

I have the same issue. I think it has something to do with APFS-formatted SSD, which if you have a recent MBP is likely the case. Also an issue in High Sierra. Time Machine needs a major upgrade to be compatible with the new file system. I have yet to see a solution to this problem that works for me, and I have tried just about everything.

I have this problem with Mojave too, on an iMac with 3TB fusion. I back up to a NAS, and have about 26TB of internal & external HDD in total. My used space is about 14TB. This bug has used up 34TB of space on my NAS since the start of a fresh backup which has been running a week now and still not completed. The last part of the of the backup, lets say 100MbBstarts and at 80MB it adds 20MB to the part remaining and then keeps increasing. It never stops.

My Mac Mini & MBP both with SSD and Mojave work normally and the backup completes on those.

No solution here either. I've trawled just about everywhere I can think to find an answer.... My backup was working fine under all previous versions of MacOS..... was even working when I migrated to a new SSD.... but then fell over under Mojave!! My usual Time Machine backup was to my Synology NAS DS918+.... tried everything I can think of to get it all working there, to no avail. I've also tried using external HD's. Nothing. I get to the last minute of completing a backup, and then the backup keeps increasing. As with others, my rather small 240Gig expected backup increases to fill whichever destination I am trying to back up to.

I've used Macs for around 8 years now, having been a late convert after over 20 years of PC's. Since moving to Mac's I've been singing their praises , but given Apples apparent lack of support for this (and other) considerable issues ... I'm no longer inclined to advise anyone to invest in a Mac.

I have this question too