Originally Posted by Keter

Lower price after changes today is most likely thanks to temporarily suspended US taxes than lower fares, something I detailed in one of my posts above. When things go back to normal DL may like to collect extra tax again.

As a side notice I am not confident with my knowledge on how taxes shall be recalculated during ticket exchanges - my understanding was that taxes are always current, however, it does not seem to be the case. For example, QF policy is to keep original taxes, however, this only applies to first exchange (or to be more strict taxes are calculated as per the day of the previous ticket issue rather than on the reissue date). MH confirmed to me that they will not charge me new Malaysian departure tax since my original ticket was issued before the tax was introduced (however, a first agent wanted to charge me that tax amount, so frankly I am not convinced the MH policy is to keep taxes as per the original ticket issue date).
Will be happy to get more knowledge on this!