The reflex
You carry a subject nobody else knows. You are asked about it all the time, and you never have time to pass it on.
The builder’s reflex
Choose one part of that subject and pass it to someone else.
Why
Being the only one who knows means being the only one who can. You cannot take leave, move to a more interesting subject, or step up. Making yourself replaceable on one subject frees you for the next.
You prepare a monthly report nobody else knows how to do. A colleague learns part of it. You do one case together, then she does one with your help, then alone. After three months, you are no longer the only way through.
Start small: one part, one person, one case. Hand over what gets prepared first, then what gets checked; what gets authorised comes last.
If your environment gives you no time to pass things on, ask for it explicitly: passing on is work, done on work time.
Try this
Choose an activity where you are the only one. Find a willing person and book three slots: they watch, they do it with you, they do it alone.
When they can act alone, tell the team clearly.
To discuss
On which subject is one of us still the only one who can act?