Write to hello@tuxedotimeguy.com. It is read by a person and you will get a reply.
Reporting a bug
The two things that make a bug fixable are your browser and device — "Safari on an iPhone 14" is enough — and what you expected to happen instead. If a timer or alarm misbehaved, the duration you set and roughly how long it actually took are the details that matter most.
Feature requests
Genuinely welcome, particularly from teachers, coaches and anyone who uses these tools professionally all day. The specific thing you are working around is more useful to hear than the feature you think would fix it.