According to this article in the Afghanistan Times, it looks like there is a diplomatic spat between Tehran and Kabul over the election of Afghan President Ashraf Ghani. Iran never supported Ghani for president but instead backed his rival Abdullah who proclaimed himself the rightful president. The election was reportedly tainted by allegations of fraud in 2019.
Tensions escalated between Washington and Tehran when the United States killed Iranian Revolutionary Guard’s Quds Corps commander Qasim Suleimani. The Iranian Abassador informed Kabul that it would not wage a military attack on Afghanistan but would make a decision on whether to attack the American military bases in the country. Afghanistan foreign ministry subpoenaed Iranian ambassador to Kabul over this. This spat has resulted in both sides expelling diplomats from each other’s respective countries. However, there has been no indication that Iran and Afghanistan have severed relations.
However, this might be something worth keeping an eye on.