I would love for the UK to rejoin the EU, but the survey results mentioned in the article don't really support the claim that there is a general desire to do so. A shift from 52% against to 52% in favor of EU membership is really not that significant.
Why specifically 3 years? Any other time frame will not support your argument? There is no trend on either direction currently, has not been for 1.5 years.
Brexit happened at the end of January of 2020, so 3 years is really the only viable amount of time to consider {since this year isn't over to be considered).
This is not a "will the UK try to rejoin one day" trend, this is a brexit regret trend.
The people responding "rejoin" to these polls probably imagine that EU accession will be done on the previous terms. If you did the same graph but made it clear to pollees that rejoining would entail a switch to the Euro and many more legislative constraints, it would almost certainly read overwhelmingly "Stay out".
Go read literally any statement from EU officials on the subject. The Euro must legally be adopted by any country which has a good enough economy (exemptions aside such as the UK or Danemark IIRC).
Sweden benefits from a loophole where they legally have to switch to the Euro but haven't started the process yet. However, there is not a chance in hell that the EU would give the same leniency to the UK, both for political (that'd make us look "weak") and financial (the British economy is several times larger than Sweden's) reasons.
The UK getting to keep the pound in a rejoin scenario is a delusion. Or at the very least the political hurdles must be made clear because it is anything BUT given (and should I remind you how the last 8 years of negotiations with the EU went?)