Just to be very pedantic, since this was a c=-1 task, and since the subproject uses Gerbicz checks to detect random hardware errors during the calculation, the original computation by boss's computer was only a PRP test.
As of now, I can still see the task, and it says:
Gerbicz check is requested, switching to PRP.
Starting probable prime test of 3*2^18924988-1
Of course, the prime has been rigorously proved prime afterwards (with an N+1 test without Gerbicz check, first on PrimeGrid's hardware using LLR, then on the Prime Pages' hardware using PFGW).