In BB house many people are wearing masks on their faces and when some incident happens that unmask them then a wise person who make his decision based on his own judgment rather than herd mentality change his opinions about them. Following critical incidents happened in last week that make Praneet realize that who's fair and who's unfair, who's good and who's evil and that's why he changed his loyalties.
1) Karishma & Gautam's yes/no cards task:
Praneet praised Gautam for his selfless decisions and immediately hugged him when he came out of confession room
2) Upen nominating all P3G Members:
He realized that Upen is also a biased person who can give shallow reasons to nominate all the members of the opposite group.
3) Upen talking harshly with him on coming late:
Though upen was right but even then Praneet was expecting a polite and soft way of talking by Upen as he always was but realizing that Upen can talk angrily and harshly too shocked Praneet a bit.
4) Aarya, Diandra, Sushant gang up against him:
Praneet took side of Aarya in Puneet's violence issue. Though he did not voiced his opinion that loudly and was not part of bedroom plotting gossip but he said that what happened to Aarya was unfair so he was shocked on that gang accusation against him.