I use IJwtService with the following code to generate access token:

        var credentials = await jwtService.GetCurrentSigningCredentials();
        var tokenDescriptor = _jwtSecurityTokenHandler.CreateJwtSecurityToken(_issuer, _issuer,
            new ClaimsIdentity(claims), expires: DateTime.UtcNow.AddMinutes(60), signingCredentials: credentials);

I get here:

System.NotSupportedException: 'IDX10621: 'Microsoft.IdentityModel.Tokens.SymmetricSignatureProvider' supports: 'Microsoft.IdentityModel.Tokens.SecurityKey' of types: 'Microsoft.IdentityModel.Tokens.AsymmetricSecurityKey' or 'Microsoft.IdentityModel.Tokens.SymmetricSecurityKey'. SecurityKey received was of type 'Microsoft.IdentityModel.Tokens.JsonWebKey'.'

Might be related to

Workaround is not to use HS256