Absorbing the mercenaries is a means of conscripting an army and paying them Russian Army rates. That was what Prigozhin was pissed about. The breaking of a promise to his men. “We know who your families” sign here was Putin’s double cross. Note the Russian General  Armageddon who sided with Prigozhin has also been made to disappear.

President Vladimir Putin has ordered Wagner fighters to sign an oath of allegiance to the Russian state after the plane crash that is believed to have killed Yevgeny Prigozhin, the mercenary group’s volatile chief.

Source: Putin issues loyalty oath ultimatum to Wagner fighters