Aren't percentages typically rounded? I don't see any US results where it's reported that X candidate got 51.31112341% of the vote even if that's correct. More likely they would announce 51.31% or maybe even just 51.3%.
So Biden is reported as receiving 51.3% of the votes which is reported as exactly 81,284,666 votes. Though clearly if you sum all the votes and calculate Biden's share, you would not get exactly 51.3% but some other number, perhaps 51.31112341% (couldn't do the actual math as the page only reports Biden and Trump's votes but I believe there were other very small candidates who must have received some small number of votes). And if you took exactly 51.3% of all votes you would not get 81,284,666 but some other number close to that.
So I don't follow what's suspicious here? (As to whether there was election fraud or not, that's a completely different question, not commenting on that here.)
Update: Never mind the above, I had in my haste misread/misunderstood the point of the article :/ (see reply below)
It seems you only skimmed the article. The concern is not rounded percentage points.
The concern is that the total votes happen to be the closest integers possible to come up with exactly those single-decimal percentages. Indicating that the total votes were derived from the percentages, not from an actual tally of votes.
It's HIGHLY improbable that out of 10,058,774 votes, the distribution between Maduro, Gonzalez, and "Other" would all yield percentages that are effectively 1-decimal percentages.
In fact, just looked up these results by CNN: https://www.cnn.com/election/2020/results/president
So Biden is reported as receiving 51.3% of the votes which is reported as exactly 81,284,666 votes. Though clearly if you sum all the votes and calculate Biden's share, you would not get exactly 51.3% but some other number, perhaps 51.31112341% (couldn't do the actual math as the page only reports Biden and Trump's votes but I believe there were other very small candidates who must have received some small number of votes). And if you took exactly 51.3% of all votes you would not get 81,284,666 but some other number close to that.
So I don't follow what's suspicious here? (As to whether there was election fraud or not, that's a completely different question, not commenting on that here.)
Update: Never mind the above, I had in my haste misread/misunderstood the point of the article :/ (see reply below)