Select or filter Length of string contained in JsonB column

[slava-se]

EF Core 8.0.7

I have a table MyEvent which contains a JsonB "Description" column which is an object containing 2 strings:

    public class MyEvent
    {
        [Key]
        public int Id { get; set; }

        [Column(TypeName = "jsonb")]
        public Translations Description { get; set; } = null!;
     }

public class Translations
{
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
    public string? En { get; set; }

    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
    public string? De { get; set; }
}

Data is definitely there as I can select it and it's Length is 756.

            var result = await _dbContext.MyEvents
                .Where(e =>e.Id == eventId)
                .Select(e => e.Description.En)
                .SingleAsync();

But if I'm trying to select the Length then it throws the System.InvalidOperationException: 'Nullable object must have a value.'

            var result = await _dbContext.MyEvents
                .Where(e =>e.Id == eventId)
                .Select(e => e.Description.En.Length)
                .SingleAsync();

Trying to use it as a where filter returns false even though it should be true.

            var result = await _dbContext.MyEvents
                .Where(e =>e.Id == eventId && e.Description.En.Length)
                .SingleAsync();

Is Length not yet supported and I have to load the data to evaluate it's length?
I've checked the docs and couldn't find anything useful