Thanks for your patience while I took a closer look at this.
The trial ads that are being displayed, are displayed for everyone and is expected. This is because some people are still interested in Spotify's offers, even if they aren't eligible for them. They often decide to get a trial offer as a present to a relative or significant other and pay with their own payment method, and due to that Spotify can't limit the trial ads only to people who never used Premium in their account.
In your case, I can see the sentence saying users who canceled after April 14, 2020 aren't eligible - but it's just of an informational statement in order to let people know if they are eligible. The message also lets them decide if they can buy the trial for someone else or not depending on the cancellation date.
I hope this clears things up!