LT8609SI and LT8609SE

Dear experts,

I have a question about the differences between LT8609SI and LT8609SE.

In the datasheet of LT8609S, both of LT8609SI and LT8609SE have the same Operating Junction Temperature Range, -40 to 125 degrees.

But the datasheet says that LT8609SE is guaranteed to meet performance specifications from 0 to 125 degrees junction temperature, on page 3.

Is this mean that LT8609SE is not examined under the conditions of  below 0 degrees?

Is it not recommended that operating LT8609SE in below 0 degrees of ambient temperature?

What can we assume when operating LT8609SE in below 0 degrees?

Now it's very hard to buy LT8609SI. Is this situation due to PCN 19_0067?

You don't have a plan of EOL of LT8609SI,  right?

Thank you in advance for your help.

Sincerely.

HATTORI, Tsutomu