An issue was discovered in Mbed TLS before 2.28.9 and 3.x before 3.6.1, in which the user-selected algorithm is not used. Unlike previously documented, enabling MBEDTLSPSAHMACDRBGMDTYPE does not cause the PSA subsystem to use HMACDRBG: it uses HMACDRBG only when MBEDTLSPSACRYPTOEXTERNALRNG and MBEDTLSCTRDRBGC are disabled.