Freezers are no problem at all, as long as it's sealed and preferably vacuum packed. The condense isn't a problem because it's sealed and below zero degrees. Water won't move when it's below 0 degrees.
Green tea has still the most water content left, so if not frozen the oxidation process will continue, and go faster than other types. It starts to turn yellow in a few months.
It's a common practice in China for tea merchants. Because good green tea is sourced in spring and you want to keep it fresh the whole year until the new Spring batch is available. I usually even keep a small sample of green teas for up to 5 years, because I can compare the same tea from the same grower for all the years and see if they've improved. It's surprising to see that even the 5 year old sample still looks really good when kept frozen.
If it's cheap green tea, then never mind. It's probably already pretty mediocre when it's purchased.