What I expected to happen was...
Attacking mobs with AbsorptionAmount set to 2049 or higher will still be calculated correctly as in previous versions
What actually happened was...
Even if AbsorptionAmount is set to 2049 or higher, it will be treated as if it were 2048.

Step to reproduce

Run the following commands in order.

/summon creeper

/attribute @e[type=creeper,limit=1] minecraft:generic.max_absorption base set 20000

/data modify entity @e[type=minecraft:creeper,limit=1] AbsorptionAmount set value 20000f

Then attack the mob and get the data using the command below.

/data get entity @e[distance=0.5..,sort=nearest,limit=1] AbsorptionAmount

Data is displayed as damage based on 2048, not 20000.

In previous versions, it was possible to set a value much larger than 2048 because the maximum value was not tied to an Attribute, but this is no longer possible in the current version.