Statement-1: Lanthanoid contraction is more important than actinoid contraction. Statement-2: Chemistry of elements surrounding the actinoids are much less known at the present time.

In comparison to 4f orbitals, 5f orbitals have a worse shielding effect. As a result, actinides' valence shell electrons experience a bigger effective nuclear charge than lanthanides do. As a result, lanthanoid contraction is less effective than actinoid contraction.
The chemistry of the substances that surround actinoids is now considerably less understood.