If the plan uses a fiscal year, it's possible that participation in 2024 could make you covered for 2025. For example, if the plan uses a fiscal year ending June 30, you separated from service in September 2024 while having made deferrals to the plan from your pay though the date that you separated from service, you would be covered for 2025 because additions were made for the plan year that ends on June 30, 2025.
However, because you were not employed with the company in 2025, you will not be receiving any 2025 Form W-2 that would be marked to indicate that you were covered by a retirement plan. To truly know if you were covered for 2025, you would need to find out from the plan whether additions were made to your account for the plan year that ended in 2025.
