According to the rules, only the winner of the league playoffs will promote.
Last season, there was an additional promotion after the promotion where additional bots were relegated as far down as possible, and active teams were promoted.
Last season in the LBBL there were 5 bot teams. Somewhat oddly, they finished 1st, 1st, 2nd, 5th, and 8th. The team that finished 8th relegated normally to D.II, along with a 6th, 7th, and 8th place teams that were active. These teams were replaced by the 4 playoff winners from D.II (3 of these teams also won their conference regular season, and one was 2nd place in the regular season).
Then the remaining 4 bots in the LBBL were replaced. It appears that the 4 teams that promoted were conference winners. It didn't matter if they lost the first game of the playoffs or lost in the finals. The 8th D.II conference winner was a bot, so they relegated to D.III. I don't know what tie-breaker would have been used, since none was needed in this case.
Last season from my league in D.IV, 6 teams promoted. The playoff winner was a bot, and they promoted, and then were instantly relegated into another league. Then 5 other teams were promoted, including 2 1st place teams, 2 3rd place teams, and one 4th place team (both 2nd place teams were bots - including the playoff winner).
There is really not a guarantee that the bot cleanup will be done every season, but I think it is extremely likely. In some cases, it will be mild, such as last season in the LBBL where all promoted teams from D.II were conference winners or playoff winners. In other cases, it could mean that almost all the teams in a league will promote.