Collation_connection always set to utf8mb4_0900_ai_ci on a database created with utf8mb4_0900_as_ci

[TheSmallGrove]

Hallo everyone,

I've an issue with the collation utf8mb4_0900_as_ci (Accent Sensitive) I used for creating everything in a database. Once I connect to the database (I use EFCore 9.0 with POMELO), I get an error when I try to use NULLIF with simple string.

NULLIF(s.Code, '')
ERROR: Illegal mix of collations (utf8mb4_0900_ai_ci,COERCIBLE) and (utf8mb4_0900_as_ci,COERCIBLE)

I need to explicitly cast the string to have it work
NULLIF(s.Code, ('' COLLATE utf8mb4_0900_as_ci))

Deeply investigating this issue I found that the variable 'collation_connection' is always set to 'utf8mb4_0900_ai_ci' (Accent Insensitive) also if I use

SET NAMES 'utf8mb4' COLLATE 'utf8mb4_0900_as_ci';

or also

SET SESSION collation_connection = 'utf8mb4_0900_as_ci';

I also tryied to put there SETs in the "init_connect" variable without any change.

Do anyone faced the same issue? What I'm doing wrong?

Thanks in advance.