Team A is losing by X points.
At the end of the game, either they draw or Team A wins.
Which is the largest X?
I can 100% confirm these two as being the equal highest from 2009-2013:
Data from 2008 and beforehand only shows the half time score and full time score, which may exclude some comebacks that are larger than this, but none exist from half time, so with the data available, the above is the record. Sometimes if you can't find a statistic, you have to work it out manually yourself.
Since the question includes a draw as the result, the biggest deficit is now 24 points.
At half-time on Saturday March 16th 2019, Scotland were 31-7 down to England at Twickenham. They overcame the deficit with 31 unanswered points before England scored a converted try in the last phase of the match to draw 38-38.
Wales came back to win 19-24 vs France, after trailing 16-0 at halftime during 6 Nations 2019. I believe this is now the biggest defict.