…but then the question is still: what changed, making TTN use RX2 now, assuming it previously used RX1 which was then hiding the problem of the wrong RX2 settings?
Maybe the above “init parameters” includes some mac set dr 0 to use SF12, which was not there earlier?
(As an aside: using SF12 indeed increases the chance that the OTAA Join Request is received by at least one gateway, but also implies that your node might keep using SF12 after its join and hence needs a lot of air time. If the node is not moving then make sure to enable ADR when joining at such high SF. When the node is moving, then you should not enable ADR, but then note that using a fixed SF11 or SF12 is not allowed.)