Before, you knew any trial gave you 30 free days. Now the free period could be shorter — maybe 7 days, maybe 14 — depending on the plan, your country, and where you sign up. Since the trial turns into a paid subscription automatically, a shorter trial means the first charge can land sooner than you expect. TradingView does say the length will be shown when you sign up, which limits the harm.
“The duration of the trial may vary depending on the plan, region, and platform, and will be shown when the user signs up for the trial.”
What you can do — When you start a trial, note the exact end date shown at signup and set a reminder a day or two before it. Cancel in the billing section of your Settings page if you don't want to be charged — an email or support ticket does not count as cancelling.