Minulta tulee helposti juotua liikaa kahvia iltaisin.

Because Finnish has a common pattern where the person is marked with -lta/-ltä and the action is presented as something that happens on that person’s part.

So minulta tulee juotua does not mean literal movement from me. It means something like I end up drinking or I happen to drink.

This makes the sentence feel less direct and less deliberate than minä juon.

Because minulta is not a nominative subject.

In Finnish, the finite verb normally agrees with a nominative subject. Here there is no normal nominative subject, so the verb stays in 3rd person singular: tulee.

That is one of the clues that this is an impersonal-type construction.

It is a very common Finnish expression meaning:

• end up drinking
• happen to drink
• find oneself drinking

In this sentence, it describes a tendency rather than one single event. So the overall idea is I tend to end up drinking too much coffee.

It is not the basic infinitive juoda.

It is a special non-finite verb form used in this pattern. For a learner, the easiest way to handle it is to learn the whole chunk:

• tulee juotua = end up drinking
• tulee syötyä = end up eating
• tulee ostettua = end up buying

Technically, juotua is a participial form related to juotu, but you do not need the full grammar label to understand the sentence.

Not exactly by pure accident, but it usually suggests lack of full intention or control.

The nuance is often:

• I find myself doing this
• this happens a bit too easily
• I slip into doing this

So it sounds softer and more indirect than a plain statement like I drink too much coffee in the evenings.

Because liikaa = too much takes the following noun in the partitive:

• liikaa kahvia = too much coffee
• liikaa aikaa = too much time
• liikaa kirjoja = too many books

Also, coffee is a mass noun, so Finnish naturally uses the partitive when talking about an unspecified amount of it.

Because iltaisin means in the evenings or on evenings, with a repeated or habitual sense.

By contrast:

• illalla = in the evening, often one specific evening or one time frame
• iltaisin = in the evenings, regularly or habitually

Since this sentence talks about a tendency, iltaisin is the natural choice.

Here helposti is not mainly about something being physically easy.

It means something more like:

• readily
• all too easily
• without much resistance

So minulta tulee helposti juotua suggests I all too easily end up drinking.

The basic meaning is close, but the nuance is different.

• Juon helposti liikaa kahvia iltaisin = a more direct statement about what I do
• Minulta tulee helposti juotua liikaa kahvia iltaisin = a softer, more indirect way to say it, with the feeling that it happens almost by itself

The second version is especially natural when you want to describe an unfortunate habit rather than a deliberate choice.

Not the normal Finnish passive like kahvia juodaan, but it is impersonal or passive-like.

There is no normal nominative subject, and the action is framed as something that happens rather than something the speaker directly announces doing.

So it is not a standard passive, but it does have that same kind of impersonal feel.