Bug: Tie Break calculation wrong?

In this tournament: lichess.org/swiss/1OTAy7SA
3 players took part. Player 3 joined late.
3 games were played.
The top players (Player1 & Player 2) played a draw and both won against the third player.

P1 vs P2: draw
P1 vs P3: P1 wins
P2 vs P3: P2 wins.

This is the result:

P1: 2.5 (0.5 + 1 + Bye:1)
P2: 2.5 (0.5 + Bye:1 + 1)
P3: 0.5 (Bye:0.5 + 0 + 0)

So my expectaion was, the Tiebreak should be

P1: 0.5 * 2.5 + 1*0.5 = 2.75
P2: 0.5 * 2.5 + 1*0.5 = 2.75
P3: 0

But the result was

P1: 0.5 * 2.5 + 1*0.5 + ??? = 3.25
P2: 0.5 * 2.5 + 1*0.5 = 2.75
P3: 0

Is this a bug in the calculation of the Tie Break, when players show up late?

I'm not 100% sure how it's actually implemented (you'll probably find something in the code on GitHub), but I think it has not much to do with the player showing up late here, but with the byes of players 1 and 2.

According to this FIDE recommendation handbook.fide.com/files/handbook/C02Standards.pdf a bye is calculated as a win against a virtual opponent who has the same number of points as the player getting the bye before that round. The virtual opponent gets a draw for each round after the bye.

So the tiebreak calculation for players 1 and 2 would be:

P1: Draw against P2 + Win against P3 + Win against virtual opponent with same points before round 3

P2: Draw against P1 + Win against virtual opponent with same points before round 2 + virtual opponent drawing in round 3 + Win against P3

P1: 1.25 + 0.5 + 1.5 = 3.25
P2: 1.25 + 0.5 + 0.5 + 0.5 = 2.75