Я заметил протечку под раковиной и оставил заявку в приложении.

I noticed a leak under the sink and submitted a service request in the app.

Breakdown of Я заметил протечку под раковиной и оставил заявку в приложении.

• я: I
• в: in
• и: and
• под: under

Questions & Answers about Я заметил протечку под раковиной и оставил заявку в приложении.

Why does it say я заметил and not я заметила / я заметил(а)?

Заметил is the past-tense masculine form, so it implies the speaker is male. A female speaker would normally say я заметила. (In writing you sometimes see заметил(а) to cover both genders, but in normal sentences you choose one.)

What tense is заметил and оставил? How is past tense formed in Russian?

Both are past tense. Russian past tense is formed from the infinitive stem + -л (often) + a gender/number ending:

• masculine: -л → заметил, оставил
• feminine: -ла → заметила, оставила
• neuter: -ло
• plural: -ли

Are заметить and оставить perfective or imperfective? Why does that matter here?