Pentair pump goes between running quietly to very loud

Hi, our pump is only about a year or two old and it gets really loud. When it first turns on it runs nicely but after a few minutes gets very loud, and will sort of go in between quiet and loud. We’ve tried all the tricks for loud pumps ie… mounting, cleaning impeller, pool is filled, no cavitation i can see and I don’t think it’s the bearings( I guess it could be but our last pumps bearings went out and it sounded different). Anyone know what this sound is? They haven’t said anything but I feel bad for the neighbors lol. Any help would be awesome! I put in a couple links of it running. One quietly and one when the noise starts up. In the noisy one you can hear it get a little quieter and then loud again.