A company's debt, cash and revenue change every quarter, so a stock that was compliant when you bought it can fail later. This is common, not a sign that you did something wrong.
The common guidance
Many scholars and screening bodies advise exiting the holding within a reasonable time after it becomes non-compliant, and not adding to it. Some allow a short grace period, for example until you can sell without a clear loss, while others ask for prompt action. The opinions differ, so follow the scholar you trust.
What about the profit?
Under the commonly cited approach, gains made while the stock was compliant are yours. For the period after it failed, scholars generally say the share of income that was impermissible should be purified, and some advise giving away any gain made after the date it failed. Ask your scholar how to treat that part.
Questionable is a warning, not a failure
Sanad marks a company questionable when it is close to a limit, with debt between 27% and 30% or interest income between 4% and 5%. It still passes, but it could flip with the next results. That is a good time to decide in advance what you will do.
Stay informed
Save the stock to your watchlist. Sanad Pro sends an email when a verdict changes, so you hear about it when it happens rather than after.
This is general information, not a fatwa.