That's a huge loan for a single building, especially only a 600 footer. Though previous articles did say this would approach $2000/sqft which is loco. That's $2M for a 1k sqft 1 BR.
And $527M loan for a 150 unit building - and that's just construction cost. You do the math
https://therealdeal.com/miami/2024/09/04/related-integra-score-527m-loan-for-st-regis-brickell/
This also mentions the 50 floor figure which is up from the previous 47. So it could be a bit taller now and possibly approaching 700 ft.