Saddle started to hurt after years of riding
Whether we like it or not, we all change every moment. Because we are alive. The differences are slight, but they are cumulative. Any change in activity, diet, lifestyle, etc. changes our body. Saddles are only getting old.
Pain isn't just an inconvenience - it's your body's way of talking to you:

constant little pain when you get tired of translating: 'enough for now, I'll fix minor problems',
increasing pain: 'stop, at least slow down, I need more time to fix myself'
muscle pain the day after training: 'you did it wrong, don't force it anymore'
sharp pain: 'STOP !! Never do that again'

If your lifestyle has changed to be less active:

you have smaller muscles and you sit differently
you slouch - your spine is overloaded and you sit differently

If you have lost weight:

you have too little weight to use the suspension perfectly
Your skin is not sufficiently isolated from the bones
Your skin may be too dry to deal with it
you have a different weight distribution
you sit differently because your body is different

If you have gained weight

you have a different weight distribution
you sit differently because your body is different

Check the saddle - even a 1 degree incline can make a difference, it's a long saddle.
Check your ... body - take 2 mirrors and look at them - you may have a new sign (no it's not cancer, cancer is vicious because it doesn't hurt until it's too late). If you find anything unexpected, go to MD and have it removed / healed.
All of the above can occur together.