Welcome to the forum @michaelblight
You’re confirming what I said in Verification errors - what do these mean?, and maybe saved me a search. Hopefully I pushed thinking about the cause further on that post, and if you’re willing to make the bug report per the directions there, it might really help understand the cause (otherwise it relies more on speculation).
If you’re technically inclined, I can say more, plus you might be able to take the look in DB that I mentioned.
This is one of the common ways to hit this issue (did your search find it?), but usually without a container, however that shouldn’t matter – it’s been thought to happen more on a file that’s changing during backups.
I don’t know Docker path mapping well, but if you are having Duplicati back up its own database journal, that’s an invitation to trouble per file-changes-during-backup. Your job Database page will show whether 73688870807967659085.sqlite is the database for the job. This gives details on what journal suffix says.
Please review the other link, and I’d be happy to point to code, if you code. Theory is short read happens, however file then gets appended so more blocks can be fetched. Short block in the middle breaks things when search is made for a –blocksize sized block of the right has, but only a shorter one could be found. Look at your two errors. It wanted size: 102400, found the expected hash, but found size 77448, so error.