I too am unable to locate any such IRS guidance regarding the transition rule alluded to by the Bard AI chatbot, so such a transition rule might not actually exist. AI chatbot's are well known to simply make stuff up. As a follow-up, you might try asking Bard to provide a link to the IRS guidance.
Even if such guidance does exist, one can always take out more than the minimum required, so the only purpose for using the old table during the transition period where the old table provided a shorter life expectancy might be if the particular investment in the retirement account (perhaps a CD) has some sort of penalty for a distribution that is otherwise not considered to be an RMD.
Also, the new Single Life Expectancy table only shows shorter life expectancies for those ages 95 through 101 and those would only apply if the beneficiary was that age in the year following the year of death of the participant. The difference is only 0.1 or 0.2 years.
It seems unlikely that the IRS would bother providing such a transition rule for such seemingly limited and relatively trivial circumstances.
