Is it normal for a bunch of new plants to die or am I just bad at this?

Hello! I started with a 5.5-gallon betta tank with live plants that were doing somewhat well until my snail kept digging them up. The tank is 6 months old and cycled. To fix that, I set up a 2.5-gallon tank (no live critters just plants) at home (sponge filter + heater) to propagate plants and let them establish roots before moving them over. I've had this tank about 3-4 weeks. Still cycling.

I’m using Fluval Stratum capped with gravel in the 2.5g (the 5.5g is just gravel for now, but I plan to add Stratum later). I’ve added small pieces of API root tabs (I thought a full tab in 2.5 gal was too much) and have Seachem Flourish, but haven’t dosed it yet because I’m worried about overdosing.

Despite this, my plants keep melting (especially Anubias). Out of every 7 plants I buy, only 3–4 survive. I’ve purchased from PetSmart, Petco, Amazon, and even drove an hour to a local fish store to get plants grown fully submerged, thinking transition melt was the issue—but I’m still losing plants. Its disheartening. Can anyone help me and tell me what I'm doing wrong?

2.5 Gallon Tank

Temp: 76F

PH: 6.4

Ammonia: 0.5 ppm

Nitrite: 0.25 ppm

Nitrate: 5-10 ppm

GH: 75 ppm

Chlorine: 0

KH: 0-40 ppm