Desk research against primary sources. Figures are traced to the issuing UAE authority and linked on the page.
Visa cancellation is a consequence of the employment ending, not a separate power your employer holds independently — it cannot legally cancel your visa while still treating you as employed. What decides whether a dismissal after probation was lawful is not what the employer believes but whether MOHRE agrees the grounds were valid if you file a complaint, so keep any termination letter and the stated reason rather than relying on a verbal explanation.
The exact length within the 30–90 day range is set by your contract, not a fixed default, so check the notice clause rather than assuming the shorter or longer end applies to you. That clause is also what a dispute would be measured against, so it is worth knowing which figure your contract actually specifies before anything goes wrong, rather than looking it up once notice has already been given.