Summary:
In Java snapshot 24w18a, now when you put on frost walker boots while not moving, ice is generated once. This change is still not in Bedrock. In Bedrock, when you equip frost walker boots, ice will not be generated until you start moving.
The Java report of the corresponding change was resolved as WAI - MC-271649.

Steps to reproduce:

1. Obtain frost walker boots.
2. Stand close to a body of water.
3. Make sure that you don't move.
4. Equip the frost walker boots.

Observed result:
Frosted ice was not generated.

Expected result:
Frosted ice was generated.

Video:
24w18a.mp4
1.21.0.24.mp4