The changelog for Preview 1.20.80.21 mentions different pack sizes for each variant of wolf. However, checking the behavior files reveals that the chestnut wolf doesn't match.

Wolf variant	Pack size from changelog	Actual pack size
Pale	4	4
Woods	Not mentioned	4
Ashen	Not mentioned	4
Black	2 to 4	2 to 4
Chestnut	2 to 4	4
Rusty	2 to 4	2 to 4
Spotted	4 to 8	4 to 8
Striped	4 to 8	4 to 8
Snowy	1	1