A transmission rarely fails without warning. It changes how it behaves first, and that is the window where a repair is still smaller than a replacement.
Slipping between gears, a pause before the car takes up drive, a shudder at low speed, or a change in how it sounds under load. None of those resolve on their own.
Transmission fluid both cools and carries pressure. Burnt fluid is a symptom rather than a cause, and topping it up without establishing why it burnt buys a few weeks.
On a manual, a slipping clutch is measurable rather than a matter of opinion. It gets measured before anything is quoted.
If it has been hit and it also needs mechanical work, it does not need to go anywhere else.