Scam or Legit: High Voltage Capacitor Manufacturing?

Here is the X7R availability table from AVX:

The highest capacitance for 0805 100V is 0.47uF; 10uF 100V is not available even in a 1206 package (I am willing to concede that the next capacitance value may be available in X5R).

Personally I would give this one a miss; AVX is one of the best sources out there and they don't make anything even close.

0805 10uF 100V ceramic = scam , The dielectric constant is not high enough

For ceramic with very thin , many layers you can achieve 10uF in small area but not 100V. You can achieve nF 10kV in 1 layer , but not 10uF at this voltage and size.

The product of these 3 parameters : size, capacity and voltage is not achievable in ceramic.

Since capacitors are highest stress components of all. Caps have the lowest MTBF, along with high demands for low ESR for performance. It is wiser to design with conservative expectations, add redundancy and derate limits to improve MTBF. Thus use more components to share the stress of ESR, ripple current, and operate < 75% of rated voltage or less. Just as e-caps have a design limit of ESRC for any ,size/family, ceramics have a design limit for VC*size which must be respected and used conservatively.

Never try to use 100% of capacitor ratings. This like buying 6000 mA Li Ion 18650 cells. They do not exist or are extremely unreliable.

1210 10uF 100V ceramic = possible but never perform with full charge Q=CV=10u*100V because charge capacity limits in size cause capacitance to reduce with raised DC voltage in ceramic.

Digikey sell Murata 0805 50V 10 uF X5R for 18.8 cents in 100s.

Digikey do not sell 100V 0805 10 uF ceramic capacitors, at all.

LCSC, an as reputable as they come high volume major Chinese distributor (located in Shenzhen) also do not sell 100V, 0805, 10 uF ceramic capacitors, at all.

For commodity items (and much else) LCSC pricing usually (not always) beats typical Western suppliers into a cocked hat.

LCSC will sell you Murata 35V X5R 10 uF ceramic caps for from US 5 cents in 150's, and 4.4 cents in 5000 quantity, and TDKs from about 11 cents in 100s.

I doubt that I need to "join the dots" re the claimed specifications of the capacitors concerned or, probably, the supplier.

LCSC guarantee provenance of products sold with money back offered if goods found not genuine. [I'd feel happier without the money back part, but it's better than you'll probably get from Ali Express sellers].