Well it is similar to how "Apple" is a trademark. They don't own the rights of the fruit, obviously, but you can't use the word "Apple" as an electronics (maybe even software) company.

There is a "Tomato Timer". [1] Looks like it was bought recently.

[1] https://tomato-timer.com/

It should be perfectly claimable within the scope of the trademark.

Peloton is general purpose term from bicycle racing, but Peloton(tm) is trademark covering e.g. stationary exercise bikes: https://trademarks.justia.com/857/75/peloton-85775447.html

I think you're arguing that "Pomodoro timer" has become Kleenexed. That's a huge risk to take, given how narrow the audience for such is to begin with. The average layperson can use the word "Kleenex" for any product in that category, but the average layperson hasn't even heard of a "Pomodoro timer".

https://en.wikipedia.org/wiki/Kleenex#Kleenex_trademark https://en.wikipedia.org/wiki/Generic_trademark