From the Social Security Trustees Report:
... The changes in policy for the Deferred Actions for Childhood Arrivals program discussed in III.B, which affect the Social Security program in the first ten years primarily by increasing payroll tax income, increased the tenth year OASI trust fund ratio by 1 percentage point. Changes in demographic assumptions over the short-range period, primarily increased mortality due to the COVID-19 pandemic, increased the projected tenth year trust fund ratio for OASI by 6 percentage points. .In case you're having trouble following the verbiage, this says that DACA is helping the Trust Funds modestly because DACA members will be paying taxes, as is, sadly, Covid-19 because of the excess deaths. Contrary to right wing fairy tales, immigration is always good for the Trust Funds. On the whole, immigrants pay taxes for many years before they draw Social Security benefits. What's hard to understand about that? The Trust funds are projected to be depleted a bit earlier despite the effects of DACA and Covid-19 because of "several changes in economic data and assumptions."
More specifically as to mortality, the report says that:
... Preliminary data for 2020 show that while the effects of the pandemic led to significantly higher death rates for those aged 15 and older, the death rates for those under age 15 were significantly lower, though not quite to the same degree. Thus, for ages 15 and over, death rates are assumed to increase above what would have been projected in the absence of the pandemic by 16.4 percent for 2020, 15 percent for 2021, 4 percent for 2022, and 1 percent for 2023. ...
As best I can tell the Trustees make no assumption about long Covid disability claims. I don't know how they could. It's all speculative at this point.