A published unsupported feature of TurboTax is that TurboTax is unable to calculate the maximum permissible solo 401(k) contribution when the individual also makes salary deferrals to anther employer's plan.
https://ttlc.intuit.com/turbotax-support/en-us/help-article/intuit-product-orders/personal-individua...
(The document published for 2023 mistakenly lists the 2021 deferral limits, but the fact that TurboTax doesn't support the calculation of the maximum permissible contribution when the individual defers salary to another employer's plan remains.)
