The leaves of your preserved plant may be dry and curled due to several reasons:
Low Humidity: Preserved plants are sensitive to humidity level. If the air is too dry, it can cause the leaves to lose moisture and become dry or curled.
Excessive Heat or Direct Sunlight: Placing the plant near heat sources like radiators, stoves, or direct sunlight can cause the leaves to dry out and lose their shape.
Improper Storage or Handling: If the plant was exposed to rough handling or extreme conditions during transport or storage, it could cause the leaves to lose their shape and texture.
Natural Ageing: Over time, even preserved plants may experience some drying and curling as part of their natural aging process.
To avoid these issues, keep preserved plants in a cool, dry environment with indirect light and avoid placing them near heat sources or in areas with low humidity.