I'm not familiar with the Tuf Pro 's', and not sure when it came out. But the original B450m Tuf boards were a 'fake' 8 phase VRM that had two lo-side and one hi-side FET (and not very robust ones at that) with 8 VCore inductors to make it look like an 8 phase in the pictures to go along with the marketing blurbs. That was shady at best and both Asus and Gigabyte did it with some of their B450 boards at launch. Once called out on it by Buildzoid and a few of the other TechTubers they relented the '8 phase' claims but the damage to their reputation was done as far as I'm concerned; they do not deserve a recommend for any of their B450 lineup at least.
In contrast, the Mortar uses a true 4 phase (they never advertised otherwise) but with paralelled lo-side and hi-side FETS, so 16 total. And they are high quality FET's with low RDS(on) and high current capability. All 16 FET's are sitting under a massive and well-finned heatsink so this is a cool running VRM. This is the same VRM design as MSI's B450 Tomahawk (Mortar's essentially the mATX variant of it), the leading B450 ATX board and a favorite for overclockers even though Zen 2 is not a good CPU for overclocking.
A good watch: Buildzoid running some thermal tests on a B450 Mortar.
View: https://www.youtube.com/watch?v=6qZW3-xZEHg