Mine does the same thing since new. I was concerned about it but things were working during warranty. I am having problems with the dining slide coming in and with the slides moving when raising the jacks. I have not proven that it is related to that "load Squeal" however.It seems to me, that noise is hydraulic related.
I'm glad you posted this. It at least tells me I am not the only one. Maybe others will chime in soon.
Larry, Stephanie Park City, Utah
2017 31SL King, 8K axles, Disc Brakes,17.5 Goodyear H tires,BU Camera,5.5 Onan, Heated HT pads, Two Uniguard Awnings, Slide Toppers, 2000w PSW inverter