This can happen even in a world created in snapshot 20w14a. I used this command that worked with 1.13 and above in said snapshot:
// /give @p minecraft:iron_helmet{AttributeModifiers:[{AttributeName:"generic.armor",Name:"generic.armor",Amount:2,Operation:0,UUIDLeast:403716,UUIDMost:847018,Slot:"head"},{AttributeName:"generic.attackSpeed",Name:"generic.attackSpeed",Amount:99999999,Operation:0,UUIDLeast:794389,UUIDMost:676379}]} 1
...And when I got the Iron Helmet and hovered my cursor over it, every time without fail, the game would crash.
Vivian Autumn
This can happen even in a world created in snapshot 20w14a. I used this command that worked with 1.13 and above in said snapshot:
...And when I got the Iron Helmet and hovered my cursor over it, every time without fail, the game would crash.