One of the biggest grips about the original Canon EOS R and the EOS RP mirrorless cameras, along with only one card slot and the 4K crop, was the lack of in-body image stabilisation (IBIS). Canon’s word on the subject was basically that they didn’t feel their IBIS tech was at a point yet where it was worth implementing. They just weren’t happy with it.
Canon promised it was going to be coming at some point in the future to EOS R cameras, though, and now that future seems to be close if Canon Watch is correct. There have been rumours that IBIS is coming to the 1DX Mark III, but now it seems one may be coming to the next EOS R mirrorless camera, too.