Correct link structure looks like this...
<a href="https://testmy.net/quickstats/johnstonf?clientTime=1">johnstonf's Speed Test Results</a><iframe loading="lazy" src="https://testmy.net/quickstats/johnstonf?clientTime=1&f=1" scrolling="no" frameborder="0" height="435" width="100%"></iframe>
I made it so it adds that for you automatically now. If you open your results with the clientTime url the output of the embed button will add that variable to the code for you.
I'll make changes to the UI later so that's not a hidden function.
Thank you