What goes around, comes around.

A few years back, the Rabbanut started to get involved in tightening up the conversion process. There were some triggers, like the incident in which a rav announced that a conversion, and possibly many more, were retroactively invalid....

The Rabbanut also announced that it was going to limit the list of rabbis and batei din from foreign countries who would be approved for performing conversions. Only conversions performed by rabbis and batei din on the Rabbanut list would be acceptable, and others would be rejected. For a Jewish convert living somewhere in the USA, the Rabbanut stance might not make much of a difference, but once that convert tries to make aliyah to Israel, he would discover that the Rabbanut does not consider him Jewish and does not qualify for aliyah.

People from smaller towns, where there might not have been a "rabbanut-approved" beis din, often had to travel to other cities to deal with the conversion issues via a rabbanut-approved beis din. Life was made  a bit more difficult for many people, perhaps justifiably.

At the same time, many rabbis were insulted and enraged that their names were left off of the approved list.

What goes around comes around.

Now, with the new conversion law on the docket for being passed, the Rabbanut is starting to be told from communities around the world that Rabbanut conversions will not be recognized by them, due to the new law (if it passes as it is expected to). Presently, London is the first to make such a statement - Chief Rabbi Lau just went to England, and the London Beis Din informed Rabbi Lau that if the law passes they will not recognize Israeli conversions as Jewish.
sources: NRG, Bechadrei

Interestingly, they are trying to come up with possible compromises and adjustments to the law proposal to make it more palatable. One of the possible solutions is that any conversion under the new law, using an ad hoc beis din created by a city rabbi for the purpose of converting someone, would require one of the Chief Rabbis to sign off on the conversion. This would keep the Chief Rabbis involved in the conversion process and would limit the "damage" possible to be done by these ad hoc batei din.
source: Kipa