Fragmentation combined with any sort of NAT is going to be fragile. For TCP traffic my recommendation is for the NAT64 to do MSS clamping to 1220 or less.
MSS clamping is a hack, but so is NAT. And most of the downsides of MSS clamping are going to be present anyway when using NAT.
I don't know if Tayga supports MSS clamping. If it does not then I think it should be added as it would probably be beneficial to a significant fraction of users.
