It seems like the Iranians see the progress they have made in their nuclear program as having given them strong leverage in negotiating.
There are other worrying signs about the negotiation prospects. Currently, the Iranians are continuing to evade the International Atomic Energy Agency (IAEA) controls. Despite two visits to Tehran by IAEA Director General Rafael Grossi, no agreement was reached to restore access for IAEA inspectors to the Karaj centrifuge assembly facility. By following their theory of "less for less", the Iranians have continued their program of activities prohibited by the JCPOA.