The first bug is with fbx. When exporting the animations are not getting recorded correctly. After importing the animations are distorted because not all the bones are translating as seen in the blender file.
The second bug is with the gltf and glb exporting. when exporting with animation sampling, only one animation is recorded for all actions. It depends on which animation was selected in blender before exporting.
The third bug is with gltf and glb exporting. Exporting the animations has something wrong with the curves. The animation keys are distorted somehow, not a good copy of what blender has. This happens without sampling.