Since (1) presumably that study includes people both with and without symptoms at those times (they don’t elaborate on methodology, so I assume they took everyone) and (2) being symptomatic makes you much much more infectious,
I would therefore take those numbers as rather serious overestimates.
This says that 16% of people remain infections at day 7 and 5% of people remain infectious at day 10:
https://ukhsa.blog.gov.uk/2022/01/01/using-lateral-flow-tests-to-reduce-the-self-isolation-period/
Since (1) presumably that study includes people both with and without symptoms at those times (they don’t elaborate on methodology, so I assume they took everyone) and (2) being symptomatic makes you much much more infectious, I would therefore take those numbers as rather serious overestimates.