There’s surprisingly little grease in these, at least in the replacement LCAs that Toyota ships. I think these tend to seep a tiny amount of oil out and then any grime cakes onto them and makes them look worse than they are.
I would spray a little degreaser and rinse them off and then watch to see if you get a lot more grease and dirt on them. My guess is this is years of slight seepage and dirt, which is normal in my similar experience. If there’s no play or vibration over bumps and they’re not making noises you might get 100k more out of them.