Setting the minecraft:generic.gravity attribute higher than 0.1 stops you from being able to jump up a block. However, setting it higher than 0.84 makes it so you can jump up one block again.
Steps to reproduce:
Set gravity to 0.84
/attribute @s minecraft:generic.gravity base set 0.84
Notice you can't jump up a block
Set gravity to 0.85
/attribute @s minecraft:generic.gravity base set 0.85
Expected behaviour:
You shouldn't be able to jump up a block, since gravity is higher
Actual behaviour:
Setting gravity value higher than 0.85 allows you to jump up a block again
Confirmed.