So far I have found 3 new stashes, all in the new expansion area. In case you wonder, the old stashes are still there, nothing has changed.
Here is the minimap with loose markings:
STASH 1:
STASH 2:
STASH 3:
Here is the wiki page with old stashes on Customs:
I also have video about them on my channel:
Source: https://www.reddit.com/r/EscapefromTarkov/comments/hz33lj/3_new_stashes_on_customs/