Q.Is it possible for gladiola bulbs to expire?
I have gladiola bulbs and I know they are old – many are likely over 20 years old (no kidding). I faithfully dig them up every late summer, and replant them in or around April. The last 2 summers they only produced a few flowers, where before the flowers were plentiful. Could it be they have come to the end of their “shelf-life”? Any suggestions on how they could be saved, or reinvigorated, would be greatly appreciated. Thank you.

Gladiola corms are most productive in the first 6 years of their life.
They often decline in flowering as they become older, so it is a good idea to save cormels to develop a continual supply of young, healthy corms.
https://www.gardeningknowhow.com/ornamental/bulbs/gladiola/storing-gladiola-corms.htm
https://www.gardeningknowhow.com/ornamental/bulbs/gladiola/care-of-gladiolas-how-to-grow-gladiolas-in-your-garden.htm
https://www.gardeningknowhow.com/ornamental/bulbs/gladiola/getting-gladiolus-to-bloom.htm