Quick thoughts on shifts
Losing Garbodor is huge. It was one of the best Pokémon in the tier and the best glue, being able to soft check almost any physical attacker that wasn't a Ground-type and setup Toxic Spikes while threatening Defoggers.
Silvally-Ghost wasn't amazing due to Tangela and Kangaskhan popularity, however it was still a restricting threat that could often clutch late game, so I'm glad it is gone.
This mon wasn't good, I don't care that it left as it never feat in my teams and I never had to even prepare for it.
These two were unviable, we won't miss them.
This mon is far from being as threatening as expected. It is slow, very vulnerable to hazards, and only Fishious Rend is hard to switch into, as even coverage moves like Freeze Dry, Psychic Fangs, and Crunch barely 2HKO what they target: Tangela can avoid the 2HKO from -SpA Freeze Dry or Band Icicle Crash lol.
This mon is amazing, we've been lacking good Steel-types for a while and we eventually got an hazard setter that hard walls standard Altaria and Articuno. Defensive sets like offensive ones are great, it is most likely going to be one of the bery best Pokémon in the tier.
Longer thoughts on current state of ZU
According to a lot of people, Centiskorch is the elephant in the room. As someone who has been wanting Centiskorch gone from the meta for months and have claimed it was unhealthy for a while, I am obviously sharing this opinion.
Centiskorch doesn't OHKO every Pokemon with the right move, it's not this type of breaker and that's why it is an unbalanced threat. The strength of Centiskorch relies on how hard it is to switch into it without using an handful of Pokemon. Centiskorch deals around 60% with all its moves to most uninvested threats and the weaker, Knock Off, heavily cripples most switchins. Due to its excellent bulk and Heavy-Duty keeping it at 100% most of the game (Leech Life recovery helps in that regard), Centiskorch is able to trade with every Pokemon that isn't carrying Rock coverage, isn't a Choice Band user, a faster threat with a super effective STAB move, and some Defense boosting sweepers.
This gives us this list of checks (only listing Pokemon above B+ rank):
Adamant Silk Scarf Kangaskhan, Sawk, Silvally-Ground, Brave Bird / Hurricane Articuno, Qwilfish, Toxic Rapidash, Altaria, Cinccino, Basculin, Coalossal, Iron Defense Cofagrigus, Cramorant, Bulk Up Gurdurr, Rock Slide Miltank, Rock Slide Piloswine, offensive Poliwrath (the best set in Choice Specs loses most of the time though), and Rotom-Fan.
Centiskorch is able to at least trade versus the rest of the tier, and a lot of these Pokemon can't afford to switch into Centiskorch because they get OHKOed by a move (Silvally-Ground, Poliwrath, and Basculin namely), a lot of them also can't afford to get Knocked Off (Sawk, Gurdurr, Cinccino) because they become unable to perform their role.
So unless you only run checks to Centiskorch which is quite restricting, you're going to need one of Qwilfish, Bulky Rapidash, Altaria, Rock Slide Miltank, Cramorant, and Coalossal. On paper, it doesn't seem that restricting to run one of these 6 sets in every team. However, they share some negative traits. Coalossal and Tangela are almost unviable if they get Knocked Off as they are taking too much damage from hazards + Centiskorch moves. Cramorant is outright of range of Power Whip after Stealth Rock or Knock Off damage, it also can't afford to Roost versus Centiskorch as Power Whip OHKOes a landed Cramorant. If you consider these Pokemon don't deal very well versus top tiers breakers like Kangaskhan, Sawk, and Silvally formes in the first place, it becomes quite hard to justifiy running them. Defensive Rock Slide Miltank is one of the most passive Pokemon in the tier, if it lacks Seismic Toss then it invites every Toxic immunity in and if it lacks Toxic, it invites almost every Pokemon in. Offensive Miltank doesn't need Rock Slide to defeat Centiskorch but it is a very niche attacker due to better Normal breakers like Cinccino, Kangaskhan, and Silvally existing.
The only two counters that are worth using are Altaria and Qwilfish, and due to Centiskorch's ability to trade with almost the whole tier, it is a necessity right now to run one of these two, unless you manage to build a team consisting only of Centiskorch checks.
Silvally-Ground is the other elephant in the room. Swords Dance / Multi Attack / U-turn / Rock Slide has almost no counter (Tangela, Pyukumuku, Thwackey, bulky Rotom, Gourgeist-Small, Gourgeist-Super, Vibrava) and is very fast. It can also afford to run variants with Ice Beam over Uturn or SD that can even 2HKO/OHKO most of those lol. Seriously, this mon has been a pain to deal with for a while and the most restricting threat in the tier right after Centiskorch (yeah because we'd still run Thwackey, Gourgeist-Small, WoW Rotom and Tangela without GroundVally, just less often). I would like to extand this point by saying currently dealing with most Silvally formes is extremely painful (Poison, Electric, Dark, Normal, and Flying mainly), because they previously were easily put in range of revenge killers thanks to Garbodor's Rocky Helmet and Aftermath, but I think that they could be less hard to handle if we didn't have two slots reserved to handle Silvally-Ground and Centiskorch, mainly because it would be easier to justify running Klinklang, Gurdurr, and Cofagrigus.
All in all, these two Pokemon are unhealthy, restrain teambuilding and make it impossible to account for several threats in the builder, mainly Silvally formes. They should be banned as soon as possible, and obviously before ZUPL which is only in a month.
Thoughts on Grassy Seed
Like I wrote in my banning reasoning, I don't think Grassy Seed was the priority to handle. A lot of counterplay was available but just hard to fit into teams due to Centiskorch and SIlvally-Ground. I still ended up voting ban on it because I thought it would be better to have less threats to account in the builder for the moment, but I believe this should be retested soon after Centiskorch and Silvally-Ground get the boot, should they.
tldr: snowslash good, arctovish meh, ban centiskorch and groundvally, keep an eye on other silvally formes afterwards and revisit grassy seed quickban.