I’m writing to provide some quick information. Trainline doesn’t handle payments and processing for the disabled person’s railcard. This is important for anyone who might find it a better option, as they can’t use the discount code on Monzo Max. I would suggest this be looked at by Monzo.
In addition to the above and as I said below - nobody else can offer the disabled railcard as it requires proof of eligibility to be uploaded. This may happen (slowly) once GB Rail takes kicks in.