Change in Shared and Unversioned Fields causing data loss in Standard value

[sitecorejp]

Do you want to request a feature or report a bug?
Yes if possible.

What is the current behavior?
After changing Shared and Unversioned Fields then run unicorn sync the value on Standard value will got lost.

What is the expected behavior?
No data lose.

Please mention your Sitecore version and Unicorn version.
SC92 revision 002893
Unicorn V4.1.1,

If the current behavior is a bug, please provide the steps to reproduce.

1, I have the following template

2, It has one Checkbox field

3, yml files:

4, Is Searchable setting

5, Is Searchable.yml

6, Is Searchable on Standard Values

7, __Standard Values.yml

8, Uncheck Shared, Unversioned on Is Searchable

9, Is Searchable.yml changed accordingly as expected

10, There is no change to Is Searchable on Standard Values as expected.

11, There is no change to __Standard Values.yml as expected

12, Run /unicorn.aspx sync then go back to Is Searchable on Standard Values and it been unchecked

13,Manually check Is Searchable

14,__Standard Values.yml changed as expected and Is Searchable field has been added UNDER the versions.

Summary:
As showing in step no.8 that after changing a template field from shared/unversioned to unshared/versioned,
It will cause data lose on the standard value after unicorn sync.

The reason because in step no.8, after uncheck Shared, Unversioned on Is Searchable, the Is Searchable
No longer a shared field.

In step no.12 during the unicorn sync, __Standard Values.yml will be used and as Is Searchable no longer a shared
and it does not have value set under the versions that unicorn will uncheck it. THIS IS CAUSING DATA LOSE.
As you can see in step no.13 and no.14, when manually check the Is Searchable, the field will be added under the versions.

I would expected unicorn to handle when there is a change of the Shared, Unversioned fields, on standard value item, add
additional check which could create an initial value of the field value under the versions per language.

I tested sitecore default serialization which won't have this behavior as the yml format are different.