I'm not sure about the lack of ambiguity.... Christmas day is on 25-Dec-2022 or is it 25-Dic-2022 (German), or is it 25-Dez-2022 (Spanish) ?

At least ISO-8601 works for everyone who uses the Gregorian calendar, which is certainly not everyone, but it's a reasonable coverage.

I could, but it isn’t my format the confuses me, it’s what other people do and what vendors set computers to etc.

There must be some language pair that has some collision with that.

In greek "June" and "July" start with the same three letters

I wonder if any languages have a different starting letter for each of the 12 months. Bonus if the days of the week are also different.