/give@p minecraft:diamond_sword{AttributeModifiers:[

{AttributeName:"generic.attackDamage",Name:"generic.attackDamage",Amount:100,Operation:0,UUIDLeast:554194,UUIDMost:850820}

,

{AttributeName:"generic.attackSpeed",Name:"generic.attackSpeed",Amount:100,Operation:0,UUIDLeast:89473,UUIDMost:653823}

]}

In 1.15.2, this exact command here would give you a sword with this amount of attack damage (in this case 100) and this amount of attack speed (in this case also 100). But now in 1.16.1, this command will give you a sword with the same attack damage and attack speed as your hands. So 1 attack damage and 4 attack speed. There is now also nothing written on the tooltips of that sword, besides durability if you have advanced tooltips on. This exact bug was also present in the 1.16 snapshots.