The Internet seems rather reluctant to explain what exactly "pixel cleaning" does, but based on the vague useless "explanations" I could find, I suspect it's a sort of "flat-field correction" where it calibrates the pixel drive current to darken the less worn and/or brighten the more worn ones so it eliminates the burn-in effect. This obviously leads to a vicious cycle where more worn pixels are driven harder and hence wear faster...

IMHO OLED is a planned-obsolescence dead-end anyway; LCDs can last literally decades, maybe with a backlight replacement, but OLEDs are designed to fail in a few years. I have a few (rather expensive) pieces of test equipment with OLEDs that became unreadable after only a few years and had to be replaced (fortunately with a regular LCD, and some firmware patching), while others with old-school CSTN/TN LCDs are still fine.