[DNS lookup should work all the time, not requiring I restart my Raspberry Pi once a day once it stops working at what seems random times.]
Actual Behaviour:
[Approx once a day the last 5 days, but less often before that, my Raspberry Pi 3B+ with Pi-Hole suddenly stops working. DNS_PROBE_FINISHED_BAD_CONFIG is shown in browsers for new pages you load. The webinterface work but no new entries since it stops working appear in the query log. Restarting the device by clicking Restart system under settings make it work again]
Debug Token:
[Debug token from when it's not working: here Debug token for when it's working after I restart the Raspberry Pi: here]
I just checked the gravity.list file and the end (or anywhere) does not contain that garbage you mention. I then checked the two log files I linked in the initial post and what you quote there is not in there either so I'm quite puzzled how you came to that conclusion @DanSchaper .
First I logged into my Raspberry Pi using SSH from a terminal, accessed /etc/pihole/gravity.list using less where I jumped to the end of the file. ssh pi@192.168.10.35 less gravity.list
Then for good measure I downloaded the gravity.list file using SFTP via filezilla on my computer and did a search through the entire file for a section of the garbage you mentioned and it didn't find anything.