Some further bisecting: It works with libegl-mesa0 19.2.6-1 libgbm1 19.3.0-1 libgl1-mesa-dri 19.3.3-1 (dpkg allows this if you upgrade libgbm1 after libeg1-mesa0 is all set) and suggesting that the package conflict is with libgbm < 19.3.0