My watch worked perfectly since before these both updates: FW 3.70 and BT 3.30.
Something (very bad) is possible to have been done. Instead improving, you are destroying this excellent watch.
And GARMIN BRASIL: the link for opening a support ticket is broken. So, that's impossible to "formally" inform you that something must be done.
I hope support can read this. There are also other users complaining about this BT issue.