Thunderbolt port doesn't work in iMac Pro

I will here assume you did not reduce the cooling and did not throttle the fan speeds at any time.

Remove the app per the vendor’s instructions.

Reset the SMC and NVRAM, then boot into Safe Mode, and try again. (This should clear most saved state.)

Do try a different Thunderbolt cable—unlikely to be the problem, but an easy fix.

If that all fails, use the Get Support link in the upper right of this webpage, and check with Apple.

Can you confirm the marking on that cable is a Thunderbolt, on the off chance that’s a charging cable and not a Thunderbolt cable? About the Apple Thunderbolt 3 (USB-C) Cable - Apple Support

Failing that, contact Apple Support.

A charging cable is a USB cable, and not Thunderbolt.

Thunderbolt doesn’t work with a non-Thunderbolt cable.

If you inserted a non-Thunderbolt USB charging cable into a USB-C Thunderbolt port on a Mac, you will have gotten USB 3.0 connection, and not Thunderbolt. Most Apple Mac USB-C ports are multi-protocol; USB 3.x, Thunderbolt, and USB PD power delivery.

A charging cable will not damage a USB-C connection.

Confusingly, USB-C is a connector spec. Not a protocol spec. Different USB-C sockets can support different protocols. USB-A connectors had USB protocol connections (USB 1.1, 2.0, 3.x), and low (2.5W, 5W, 10W, or 12W) power.

Adding to the confusion here, a USB-C Thunderbolt cable can pass both Thunderbolt and USB 3.0.

If you’ve gone through the previously suggested hardware resets, and are now using a Thunderbolt cable to connect to Thunderbolt, contact Apple.