The Kaldheim card isn't a counter spell, it's a polymorph for spells. Countering isn't in reds color pie, so this would need blue in its cost.
I think it's kind of like Planar Chaos, a very red and not at all blue-feeling card. I think maybe the reactivity of the instant version makes it seem less red. A card like Red Elemental Blast feels red when you counter a counterspell with it. What do you think about this one?
Uncertain Steps1R
Enchantment
Whenever a player casts a spell, flip a coin. If you win the flip, counter it and sacrifice Uncertain Steps.
We've got something less reliable than Lunar Force or Hesitation, but something that feels red to me.
I think Standstill could also be kitted with a coinflip and suddenly be red as well.
Tibalt's Trickery isn't at all like Planar Chaos. Planar Chaos is a very obvious break justified with "lol random". While Red Elemental Blast is part of the distant past where "my enemy can do this so I can do this to my enemy" was a valid justification for abilities being in the wrong color.
Tibalt's Trickery is a Transmogrify for spells. This ability has only ever been part of red's(possibility storm) and colorless's(Knowledge Pool) part of the pie.
Red doesn't get counterspell in the same way that blue doesn't get destroy target creature despite pongify using those exact words.