I've had the same 8GB USB 2.0 Sandisk flash drive for years that was used for logging on a mikrotik hAPac and a RB951G-2HnD before it without any issues. Since then I've upgraded to the RB5009 and have been using it for both logging and storing/running 2 containers - bonjour-reflector and AdGuardHome. I've confirmed that if it's only used for logging, everything is fine. Running just the bonjour-reflector container is also fine, however when I run the AdGuardHome container the USB flash drive will get ejected within a few hours of being connected. If I re-connect the drive and restart the container it'll run into the same issue a few hours later. At first I thought the flash drive was nearing its end of life, however I've swapped it out for 2 other USB 2.0 flash drives with the same result. If I re-connect the drive after being ejected, but do not restart the container then all it is used for is the bonjour-reflector container and mikrotik logging, both of which seem to go fine - currently in this state for almost a day and counting. anyone have any suggestions on why this is? the flash drive is formatted as ext4

I have a similar issue on RB5009UPr+S+ while running the unifi controller container. In my case, after upgrading to 7.14.1, USB disk works for only a few minutes.

Information about the USB Flash Disk connected:
# SLOT MODEL SERIAL INTERFACE SIZE
0 BM usb1 Kingston DataTraveler 3.0 B42E99B07A9FE7A1890F047E USB 3.20 5000Mbps 62 008 590 336

Any ideas on how to solve the issue are highly appreciated.