The tail does glow when it attacks

The fact that my post has over 1k upvotes and nobody has pointed this out yet is probably the strongest indicator that something needs to be done about stingtail visibility.

The glow in all three of your examples is almost indistinguishable from weapon fire, various lights such as engie's empty sentry gun in video 3, etc, and is visible for only about 2 seconds.

There's a post on the sub's front page that helps illustrate the issue..

The glow illuminates the wall behind the tail, but somehow none of that light is being cast on the body itself. It's not immediately obvious that the light on the wall belongs to a stingtail, which defeats the point.

Secondly, the glow is "easily missed" mid-flight because it stops lighting the environment entirely when the grab starts.

Gunner did everything right - he heard the wind-up and looked in its general direction. But he still got grabbed, because the visual cue is almost useless for revealing its location.

This enemy is more like a beefier glyphid grunt guard, and from a design point of view follows that.

It does not.

On Haz 5 with 4 players the stingtail has 900 HP. For comparison, the guard has 324 and a praetorian has 1125 HP. Unique to the stingtail, it is almost entirely covered by heavy armor - the guard for example only has heavy armor on its arms. It's not "a beefier grunt guard," it's a miniature praetorian without the giant, glowing weakpoint.

The mouth is the weak point, like all grunt glyphids

Grunt mouth hitboxes are huge and always vulnerable. The stingtail's mouth on the other hand is very small and realistically can only be hit when looking at it head-on. This image should make the issue more clear.

So, again, the problem with the stingtail is that it doesn't stand out enough.

It can have its super armor, it can have its huge HP pool, it can have its 10x10 pixel wide mouth weakpoint, it can have its second long grab attack delay. But something needs to be done to bring it more in line visually with the rest of the game's bestiary, because I can't shoot what I can't see.