I've been using Catalina since the beta release and am now running 10.15.4 on a late 2013 Pro 13", early 2015 13" Air, and mid-2014 Pro 13". All three MacBooks are able to read and write to all flash drives and external drives I have connected.
It could be coincidence that the drive stopped being recognized after installing Catalina.
AFAIK, the USB connection is soldered directly to the drive's logic board which makes data recovery more difficult.
Have you tried the drive on another MacBook? Is it encrypted?