Possible bug in field "weblink" > styling > default

there might be a small bug in field type "weblink"´s > config > editing > form field >  Optional Properties >  Styling (CSS) Class >
and here the dfault behavior.

[reproduce]

• create weblink field
• styling > as select
• default > space-separated css-class-names
• usage of default > the above & also display instead of empty
• select choices > some correctly formatted choices. First element's value ist equal to above default and has label "green Button".
• create content item with that field. set styling to default. (selectbox recognizes identity in ilt's elements ans says "default (green Button)")

[expected behaviour]
When content-item using that field is set to "default (green Button)", correct classes are used.

[real behaviour]
When content-item using that field is set to "default (green Button)", empty class is output

[what works]
all other styling option sfrom select-list.

[setup]
joomla 3.10.11
FC 4.1.5