I would suggest looking up the concepts of Supply Chains if you’re wondering why this is likely happening.
The Grand Creators has been delayed from January 14th to January 28th, 2022
Hidden Arsenal: Chapter 1 has been delayed from January 28th, 2022 to February 25th, 2022
OTS Tournament Pack 18 has been delayed from February 9th, 2022 to February 23rd, 2022
Speed Duel GX: Duel Academy Box has been delayed from February 25th, 2022 to March 18th, 2022
Structure Deck: Albaz Strike has been delayed from March 11th, 20220 to April 8th, 2022
No reason has been provided, but ongoing shortages with Global Supply Chains issues due to the pandemic and the ongoing difficulty to acquire cardboard for printing are the likely unspoken culprits.