That is not a typical motor failure but it is possible.
So it ran fine on a vfd for 7 years? No paramater changes in the drive?
Could be potential bad connection somewhere.
Really need to do some troubleshooting. Measure voltage to the drive, measure DC bus voltage (or read off the drive interface), measure the individual motor voltages, look at all 3 motor phase currents, read the drive torque or kilowatts off the drive interface, etc. All of these types of tests are quick and can tell you what is happening.
To test the motor the shop should of done a surge test (to validate the phase to phase/coil to coil/turn to turn insulation), DC high voltage (500 volts DC) ground insulation test to determine if groundwall insulation is good and a phase to phase resistance imbalance test using a high current low resistance meter (look for no more than 2 - 3% imbalance).
It could be as simple as a bad lug on the motor or elsewhere.
But a drive does have the capability of phasing back (slowing down) to react to some motor insulation failures. The most blatant one I saw was the a 10 hp motor was shorting phase to phase because a braze joint was sharp and was digging through the insulation into another phase. Found it with a resistance imbalance test.