Should work.
Problems with the compatibility of different RAM modules with each other cannot be completely ruled out. However, this is extremely rare nowadays.
AsRock writes on their website that 128GB are also supported on the B450 Pro4:
https://www.asrock.com/mb...Often maximum RAM capacity specifications are listed reduced compared to what is technically feasible, e.g. because there are no larger modules to test. Technically, 192GB could also work (4*48GB). However, no one has probably tested this on the motherboard yet, but other AM4 motherboards have already been certified for this.