I would recommend contacting the Canada Revenue Agency (CRA) and see if they will let you use this amount on your 2024 tax return. They might ask you to use it on an older return. 

If you are in Canada or the United States, you can call the CRA at 1-800-959-8281. If you are elsewhere, you can call 613-940-8495. This page has more ways to contact the CRA: Contact the Canada Revenue Agency

Thanks.

I closely checked my CRA account again. The "Federal Tuition ..." table shows the numbers under Current Year in prior years but all zeros under Amount Available for Carrying Forward (the last column of the table). It means I lost all the unused amount which should have been claimed first when I earned income in the 90s.