Another thing I experienced is that the original FTDI VCP driver doesn’t play well with the Apple one in Catalina. During the aforementioned troubleshooting of my telemetry radios I ended up installing FTDIUSBSerialDriver_v2_4_4 but then noticed that my other serial devices would be affected. The driver and device would work initially (after system restart) but once the device disconnected the internal representation /dev/tty.* character file would not be re-created after plugging the device back in. If you never restart the Mac but hibernate then the serial device would not come back.
In fact, it looked like the driver was being created twice with /dev/tty.usbserial-XXXX and /dev/tty.usbserial-2, when both the original Apple and the FTDI drivers coexisted. The output of the lsusb port on Darwin confirmed this; the FTDI device was displayed twice (!).
I ended up following the FTDI instructions on how to remove their driver (section 4.2 in AN_134_FTDI_Drivers_Installation_Guide_for_MAC_OSX.pdf) and things got back to normal for FTDI serial. I wonder if this is the case for you as well.