Solomon Rutzky digs into UTF-8 support in SQL Server 2019 and has found a few bugs :
Let’s start with what we are told about this new feature. According to the documentation, the new UTF-8 Collations:can be used …
as a database-level default Collation as a column-level Collation by appending “ _UTF8 ” to the end of any Supplementary Character-Aware Collation (i.e. either having “ _SC ” in their name, or being of level 140 or newer ) with only the CHAR and VARCHAR(implied) have no effect on NCHAR and NVARCHAR data (meaning: for these types, the UTF-8 Collations behave the same as their non-UTF-8 equivalents
“This feature may provide significant storage savings, depending on the character set in use.” (emphasis mine)
Solomon takes his normal, thorough approach to the problem and finds several issues.