Source: https://zycrypto.com/peter-tode-advices-users/
Bitcoin core developer peter todd , Advices users not to accept transactions with less than 6 confirmations After BIP 91 Activates.
Bip19 which was reached and agreed by about 81% of miners have come into agreement to be activated.
Todd quoted that
"IF/WHEN BIP 91 ACTIVATES, THERE'S A HIGH CHANCE IT'LL LEAD TO MULTIPLE REORGANIZATIONS. DO NOT TRUST ONE CONFIRMATION TRANSACTIONS FOR NOW; WAIT FOR SIX+ CONFIRMATIONS."
with exceptions of
If you can use other means (eg legal system) to secure payment.
More technical users who can monitor chain in detail.
Situations where actual losses in event of non-payment are tolerable (e.g. purchase of items like music with zero marginal cost).
while keen about the problem that the activation might cause todd stated that problems that issues that are likely to occur such as double spending and other related problems will be fixed after the activation and adaptation of BIP91, which might not last upto hours or days , so users should not be worried about it.