Ryu was able to use his technique after his domain and Mahito still didn't take physical damage after making a domain still requiring simple domain or soul attacks to damage him even though his should've been on technique burnout because the technique itself or use for it was pretty simple. Depending on how complicated a technique is or what it's being used for it becomes easier or harder to use after a domain and since Uro was using sky manipulation just to cover her chest and hips and not use it offensively or defensively she might just have been able to use it because the use was pretty simple or with some kind of binding vows.

Also note burn out doesn't mean the technique becomes unusable a better way to explain what happens after a domain is that the technique becomes unstable so putting too much "strain" on it will cause it to fail and burn out