It appears that there is little substantive discrimination based on citizenship status

Counter-intuitive but it is being praised for its rigor.  First seen here:

In today's episode of "selection is everywhere", many people claim based on observational studies that naturalization improves the integration of immigrants, but this study based on a random lottery finds no effect on either economic and non-economic dimensions of integration 🧵 pic.twitter.com/gKYyNn5zKv

— Philippe Lemoine (@phl43) July 13, 2023

From Does access to citizenship confer socio-economic returns? Evidence from a randomized control design by Jens Hainmueller, Elisa Cascardi, Michael Hotard,  Rey Koslowski, Duncan Lawrence, Vasil Yasenov, and David D. Laitin.  From the Abstract:

Based on observational studies, conventional wisdom suggests that citizenship carries economic benefits. We leverage a randomized experiment from New York where low-income registrants who wanted to become citizens entered a lottery to receive fee vouchers to naturalize. Voucher recipients were about 36 percentage points more likely to naturalize. Yet, we find no discernible effects of access to citizenship on several economic outcomes, including income, credit scores, access to credit, financial distress, and employment. Leveraging a multi-dimensional immigrant integration index, we similarly find no measurable effects on non-economic integration. However, we do find that citizenship reduces fears of deportation. Explaining our divergence from past studies, our results also reveal evidence of positive selection into citizenship, suggesting that observational studies of citizenship are susceptible to selection bias.

You would assume that having citizenship would make many things easier for immigrants and that ease would in turn improve income, credit scores, access to credit, financial distress, and employment.  That appears to be not the case.  We could plausibly imagine that immigrants, particularly illegal immigrants, might face all sorts of barriers and constraints which would retard their accomplishments.  This study indicates that the fact of citizenship itself has no measurable impact.  Outcomes are driven by other, yet to be identified, factors.