I'm missing the Special Guests from Strixhaven:
https://scryfall.com/search?q=e%3Aspg+cn%E2%89%A5149+cn%E2%89%A4158+game%3Apaper&unique=prints&as=grid&order=set

I'm seeing the RCQ promos for this season missing:
https://scryfall.com/card/slp/50/ancient-stirrings
https://scryfall.com/card/slp/51/sowing-mycospawn

The double-sided tokens from Secrets of Strixhaven. While the tokens are displayed on Scryfall, the double-sided element of them is not, hope this still counts:
https://scryfall.com/sets/tsos
The tokens I own are:
2x Copy (0001) // Spirit (0010)
1x Elemental (0002) // Fractal (0004)
2x Elemental (0002) // Treasure (0012)
3x Elemental (0003) // Treasure (0012)
1x Fractal (0004) // Inkling (0006)
1x Fractal (0004) // Pest (0008)
3x Fractal (0005) // Pest (0009)
1x Inkling (0006) // Spirit (0010)
2x Inkling (0007) // Spirit (0011)

Looks like the SLD MagicCon 2026/MagicFest 2026 Soul's Attendant is missing. Linked the Scryfall below:
https://scryfall.com/card/sld/7147/souls-attendant

SOS Art Series

SOS Double-sided tokens

SOC Double-sided tokens

ECL Double-faced card tokens

Are we missing the 2017 Gift Pack (G17) https://scryfall.com/sets/g17 or am I just not searching hard enough?

The following cards from the Goblin Storm Secret Lair Commander Decks got new "The List" printings (aka old art and set symbol but with the planswalker logo in the bottom left) and are missing on the site (original set name and number in brackets):

- Gempalm Incinerator (DMR #122)
- General Kreat, the Boltbringer (J25 #48)
- Goblin Dark-Dwellers (J25 #556)
- Goblin Matron (DMR #123)
- Goblin Trashmaster (M19 #144)
- Goblin Warchief (J22 #548)
- Grenzo, Havoc Raiser (M3C #213)
- Howlsquad Heavy (DFT #134)
- Impulsive Pilferer (OTC #171)
- Mogg War Marshal (DMR #131)
- Redcap Gutter-Dweller (WOE #146)
- Rundvelt Hordemaster (DMU #142)
- Searslicer Goblin (FDN #93)
- Siege-Gang Commander(DMR #136)
- Siege-Gang Lieutenant (M3C #113)
- Storm-Kiln Artist (OTC #181)
- Ancestors' Aid (LCI #132)
- Battle Hymn (AVR #128)
- Chaos Warp (DRC #48)
- Crimson Wisps (J25 #533)
- Expedite (CMR #413)
- Fists of Flame (MH1 #123)
- Great Train Heist (OTJ #125)
- Sazacap's Brew (BLB #151)
- Seething Song (C21 #179)
- Blasphemous Act (DRC #101)
- Daring Discovery (LCI #142)
- Draggon Fodder (FDN #535)
- Faithless Looting (OTC #165)
- Glimpse the Impossible (MH3 #124)
- Goblin Negotiation (FDN #88)
- Haze of Rage (TSR #169)
- Krenko's Command (J25 #140)
- Mana Geyser (C21 #176)
- Past in Flames (MM3 #105)
- Renegade Tactics (J25 #590)
- Spreading Insurrection (MH2 #142)
- Wild Ride (TDM #132)
- Witch's Mark (WOE #158)
- Idol of Oblivion (BLC #277)
- Ruby Medallion (MH3 #295)
- Swiftfoot Boots (BLC #286)
- Throne of Eldraine (WOC #28)
- Boggart Shenanigans (EVG #54)
- Frontline Heroism (J25 #15)
- Goblin Bombardment (MH2 #279)
- Impact Tremors (MOC #285)
- Quest for the Goblin Lord (WWK #86)
- Arena of Glory (MH3 #215)
- Castle Embereth (ONC #150)
- Den of the Bugbear (AFR #254)
- Dwarven Mine (ELD #243)
- Forgotten Cave (M3C #343)
- Fountainport (BLB #253)
- Hidden Volcano (LCI #277)
- Kher Keep (MKC #270)
- Reliquary Tower (M3C #368)
- Smoldering Crater (DMR #257)
- Spinerock Knoll (DSC #300)
- War Room (MKC #310)

Tokens:
- Eldrazi Spawn (MH3 #2) // Rat (WOE #7)
- Eldrazi (M3C #1) // Eldrazi Spawn Eldrazi Spawn (MH3 #2)
- Dwarf (ELD #7) // Soldier (UMA #11)
- Soldier (UMA #11) // Kobolds of Kher Keep (MKC #12)
- Fish (BLB #7) // Kobolds of Kher Keep (MKC #12)
- Fish (BLB #7) // Treasure (MH3 #34)
- Wicked // Cursed (WOE #17) // Treasure (MH3 #34)
- Start Your Engines! // Max Speed (DFT #14)

and the Red Mana (SLD 7082) counter is missing as a card completly. These printings are also missing on scryfall so I sadly can't include any image links.

Forgot to include that there is also a thick cardstock copy of Zada (https://scryfall.com/card/sld/2423/zada-hedron-grinder)Forgot to include that there is also a thick cardstock copy of Zada (https://scryfall.com/card/sld/2423/zada-hedron-grinder) and the Moggcatcher bonus card (https://scryfall.com/card/sld/7081/moggcatcher) included in the deck which are also missing from the site.