February 2019's Unearthed Arcana gave us a revisited version of the Artificer class, a magic user whose magic is stored and accessed through items instead of invocations or eldritch power.

In the description of their Spellcasting feature is the following text (emphasis mine):

You have studied the workings of magic, how to channel it through objects, and how to awaken it within them. As a result, you have gained a limited ability to cast spells. To observers, you don’t appear to be casting spells in a conventional way; you look as if you’re producing wonders through various items.

A previous post implies that you have to be able to perceive that the creature is casting a spell in order to Counterspell it.

Would a traditional caster (sorcerer/wizard/warlock) be able to Counterspell a spell cast by an Artificer?

I'm not sure if the intent of this text is simply to add flavor, or if it is meant to imply that your spellcasting is imperceptible by normal means.

The relevant portions of Counterspell, for reference:

Casting Time: 1 reaction, which you take when you see
a creature within 60 feet of you casting a spell

[...]

You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 3rd level or lower, its spell fails and has no effect.

Yes, artificers can be counterspelled

Although the "flavoring" is different, artificers' spells have the same kinds of components that other spellcasters do. In essence, rather than drawing on some innate magic or some eldritch power, or manipulating the Weave through studied techniques or through music, artificers instead cast spells by infusing magic into items and then releasing it from those items.

This distinction is described in more detail in the sidebar "The Magic of Artifice" on p. 4-5 of the UA:

As an artificer, you use tools when you cast your spells. When describing your spellcasting, think about how you’re using a tool to perform the spell effect. If you cast cure wounds using alchemist’s supplies, you could be quickly producing a salve. If you cast it using tinker’s tools, you might have a miniature mechanical spider that binds wounds. When you cast poison spray, you could fling foul chemicals or use a wand that spits venom. The effect of the spell is the same as for a spellcaster of any other class, but your method of spellcasting is special.

The same principle applies when you prepare your spells. As an artificer, you don’t study a spellbook or pray to prepare your spells. Instead, you work with your tools and create the specialized items you’ll use to produce your effects. If you replace cure wounds with shocking grasp, you might be breaking down the device you used to heal and creating an offensive item in its place—perhaps a gauntlet that lets you channel a surge of energy.

Such details don’t limit you in any way or provide you with any benefit. You don’t have to justify how you’re using tools to cast a spell. But describing your spellcasting creatively is a fun way to distinguish yourself from other spellcasters.

As the last paragraph clearly states, artificers' form of spellcasting is unique in the way it is described and roleplayed, but mechanically it has just the same components as any other class' spellcasting. As such, other spellcasters can perceive artificers casting a spell, and can counterspell them.