The state of the current metagame seems to be relatively stable. However, I definitely believe that Melmetal should be suspect tested!
Overall, Steel teams boast a solid defensive core covering all their weaknesses with different immunities and provide key resists to many types, making Steel teams defensive core frustrating to take on. While this isn't the biggest problem, the defensive core has Melmetal in the back able to take on other walls for them, its teammates provide an ample host of switch-in opportunities for Melmetal and wear down its checks, and it can break through threats for them such as Galarian Moltres. In return, Melmetal has pivots to immunities for the handful of Pokemon that can handle it. Corviknight, Skarmory, and Celesteela provide a Ground immunity, provide a handful of utility between pivoting in with U-turn, clearing hazards with Defog, clicking Body Press to weaken other Steel-types, setting Spikes, Leech Seed + Toxic support, and more. Aegislash provides a Fighting immunity and is a handy anti-Psychic tool; with Shadow Ball + Shadow Sneak alongside King's Shield, it can work against Pokemon such as Tapu Lele threaten Melmetal.
Melmetal has a few sets in the current metagame: Choice Band, Leftovers + Substitute, or Assault Vest. All these sets serve different purposes and allow Melmetal to take on a variety of different Pokemon. Choice Band being the most devastating attacker can OHKO or 2HKO the entire metagame (literally no Pokemon isn't 2HKO'd by either its STAB or coverage), even forcing types with decent matchups against Steel to warp some sets to better take on Melmetal such as Dragon using Physically Defensive Rocky Helmet Garchomp. Leftovers + Substitute trades some power for longevity; this allows it to better take advantage of forced switches by giving it a safe turn to attack whatever comes in and avoid being burnt by Pokemon such as Toxapex with Scald. Assault Vest functions similarly to Choice Band in terms of how it plays; while it trades a good chunk of power, it still hits plenty hard and allows it to take on traditional checks, such as Hydreigon on with ease.
Choice Band is its most broken set being able to hit with devastating force and 2HKO the entire metagame between Double Iron Bash and its fantastic coverage to take on Steel-resistant Pokemon such as Ferrothorn with Superpower, Magnezone with Earthquake, Celesteela with Thunder Punch, as well as good supporting coverage with Ice Punch for defensive Landorus-T and Garchomp. I don't really feel like posting a bunch of calcs since everyone knows just how ridiculously powerful this behemoth is.
TL;DR: Melmetal's support from Steel's defensive core and sheer wallbreaking ability make it too much for the metagame.
Overall, Steel teams boast a solid defensive core covering all their weaknesses with different immunities and provide key resists to many types, making Steel teams defensive core frustrating to take on. While this isn't the biggest problem, the defensive core has Melmetal in the back able to take on other walls for them, its teammates provide an ample host of switch-in opportunities for Melmetal and wear down its checks, and it can break through threats for them such as Galarian Moltres. In return, Melmetal has pivots to immunities for the handful of Pokemon that can handle it. Corviknight, Skarmory, and Celesteela provide a Ground immunity, provide a handful of utility between pivoting in with U-turn, clearing hazards with Defog, clicking Body Press to weaken other Steel-types, setting Spikes, Leech Seed + Toxic support, and more. Aegislash provides a Fighting immunity and is a handy anti-Psychic tool; with Shadow Ball + Shadow Sneak alongside King's Shield, it can work against Pokemon such as Tapu Lele threaten Melmetal.
Melmetal has a few sets in the current metagame: Choice Band, Leftovers + Substitute, or Assault Vest. All these sets serve different purposes and allow Melmetal to take on a variety of different Pokemon. Choice Band being the most devastating attacker can OHKO or 2HKO the entire metagame (literally no Pokemon isn't 2HKO'd by either its STAB or coverage), even forcing types with decent matchups against Steel to warp some sets to better take on Melmetal such as Dragon using Physically Defensive Rocky Helmet Garchomp. Leftovers + Substitute trades some power for longevity; this allows it to better take advantage of forced switches by giving it a safe turn to attack whatever comes in and avoid being burnt by Pokemon such as Toxapex with Scald. Assault Vest functions similarly to Choice Band in terms of how it plays; while it trades a good chunk of power, it still hits plenty hard and allows it to take on traditional checks, such as Hydreigon on with ease.
Choice Band is its most broken set being able to hit with devastating force and 2HKO the entire metagame between Double Iron Bash and its fantastic coverage to take on Steel-resistant Pokemon such as Ferrothorn with Superpower, Magnezone with Earthquake, Celesteela with Thunder Punch, as well as good supporting coverage with Ice Punch for defensive Landorus-T and Garchomp. I don't really feel like posting a bunch of calcs since everyone knows just how ridiculously powerful this behemoth is.
TL;DR: Melmetal's support from Steel's defensive core and sheer wallbreaking ability make it too much for the metagame.