spells still rolling with 5e rules not not 5.5e rules

Last night I used a spell I had not used before which was Blades of Disaster. When I used the spell last night, it rolled with the Forgotten Realms: Heroes of Faerun number of die for a normal hit. However later I crit on an 18 and it rolled the normal damage listed for the new rules (10d6) but it also rolled 8d12 extra damage for the crit which is from the old Tasha's rules and not the new Forgotten Realms: Heroes of Faerun rules which does not mention 8d12 force. I am playing a 5.5e character and had to reroll the extra damage as it rolled incorretly in DND Beyond. I am trying to report this, but I don't know whom to contact or if it will ever get changed. Please Help.

Tasha's: 

You create a blade-shaped planar rift about 3 feet long in an unoccupied space you can see within range. The blade lasts for the duration. When you cast this spell, you can make up to two melee spell attacks with the blade, each one against a creature, loose object, or structure within 5 feet of the blade. On a hit, the target takes 4d12 force damage. This attack scores a critical hit if the number on the d20 is 18 or higher. On a critical hit, the blade deals an extra 8d12 force damage (for a total of 12d12 force damage).

As a bonus action on your turn, you can move the blade up to 30 feet to an unoccupied space you can see and then make up to two melee spell attacks with it again.

The blade can harmlessly pass through any barrier, including a wall of force.

Forgotten Realms: Heroes of Faerun:

You create a 3-foot-long blade-shaped planar rift that lasts for the duration. The rift appears within range in a space of your choice, and you can immediately make up to two melee spell attacks, each one against a creature or object within 5 feet of the rift. On a hit, the target takes 10d6 Force damage. This attack scores a Critical Hit if the number on the d20 is 18 or higher.

As a Bonus Action on your later turns, you can move the rift up to 60 feet and repeat the two attacks against a creature or an object within 5 feet of it. You can direct the attacks at the same target or at different ones.

The blade can harmlessly pass through any barrier, including ones created by spells like Wall of Force.