Cusser
+1y
When my pedal stayed down (in 2002), I replaced both my clutch master and slave cylinders, that fixed it. Mine were under lifetime warranty, easier just to replace both and bleed the system once.
I do believe a Mazda mechanic told me it was more likely the clutch master when this happened.
I know you you stated that you replaced both not too long ago, but I still suspect clutch hydraulics.