Any long term fin users (5+ years) going through regular (heavy) sheds?

After 11 years of 100% stabilisation (arguably even thicker hair, year after year with last year as the thickest hair I (33M) have ever had...), I have probably lost 50% of my hair density in the last 6 months. Regimen didn't change at all.

Massive shed? Fin suddenly stopped working? Other causes?