The part (with Glass Material) refract things like my character in the video:
Issue: But it seems that it only happens sometimes.
The Refraction is intended with the Glass Material. If you don’t want this to happen, you may use Plastic material instead with reflection up to 0.3 to achieve a reflective surface while keeping the “caustics”. Or you can look for an animated water texture resource which can be found here in DevForum too, if I remember correctly.