How to bold text in mermaid flow chart in Github markdown?

Question

I have a mermaid flow chart in a Github markdown file which used to render correctly (text formatted as bold between the <b> and <\b> tags) but no longer does. In addition, the boxes for labels for the arrows have become semi-transparent.

Code is here:

graph TD;
    A["<b>CPRD Aurum October 2020 release</b> with linked Set 21 <br> (April 2021) HES APC, patient IMD, and ONS death data"] --> |"Unique patients with a diabetes-related medcode between 01/01/2004-06/11/2020 and >=1 year data prior and after"| B["<b>Our extract</b>: n=1,480,985*"]
    B -->|"With a diabetes QOF code with a valid date** (quality check to remove those without diabetes)"|C["n=1,138,193"]
    C --> |"Inconsistencies in diabetes type suggesting <br> coding errors or unclassifiable"|D["n=14"]
    C --> E["<b>Diabetes cohort</b>: n=1,138,179"]
    E --> F["<b>01 At-diagnosis cohort</b>: <br> n=771,678 <br> Index date=diagnosis date"]
    E --> G["<b>02 Prevalent cohort</b>: <br> n=643,143 <br> Actively registered on 01/02/2020 <br> Index date=diagnosis date"]
    E --> H["<b>03 Treatment response (MASTERMIND) cohort</b>: <br> n=995,036 with 3,218,100 unique drug periods <br> For T2D 1st instance dataset excluding drug starts within 91 days <br> of registration: n=769,394 with 1,663,398 unique drug periods <br> With script for diabetes medication <br> Index date=drug start date"]

Desired output

Current output

I know that the version of mermaid used by Github is 10.2.0; I'm not sure if that's the issue or how to change it?