What's your Mac - macOS setup? ...How do you have the external hard drive for Time Machine setup / connected?
I've been steadily using TM through all the macOS updates / upgrades (including upgrade to High Sierra & change to APFS) for the last several years, and I've not had any issues. ...I'm not discounting your issue; but, my experience hasn't been such I think there's an endemic issue with TM. As result, I'm thinking there's a particular issue with your setup that might be the root cause of your issue.
As example & given my MBP 15 (using about half of my 1TB SSD) with TB3, I connect a 7200rpm LaCie Mobile 2TB - USB-C drive via a TB3 cable (USB-C compatible) directly to my MBP. However, I regularly dismount the drive about mid-day and reconnect the next morning (& reactivate TM). I mention to highlight I'm regularly stopping / starting my TM given my MBP use pattern; so if there were some endemic bug in TM, I think I might have seen it by now.
As result, we need to dig a bit into your setup to sort out your issue.
