No me extraña la decisión.

Because me is an indirect object pronoun, not a subject pronoun.

In this sentence, the idea is literally something like:

• The decision does not surprise me.

So:

• la decisión = the thing causing the reaction
• me = the person affected by it

You do not use yo here because yo would be the subject, and in this sentence I am not the grammatical subject.

Because the verb agrees with la decisión, which is third person singular.

The subject is:

• la decisión

So the verb must also be third person singular:

• La decisión me extraña
• La decisión no me extraña

It is not agreeing with me.

A native English speaker may want to think of me as the main person in the sentence, but grammatically the verb matches la decisión, not the person feeling surprised.

The subject is la decisión.

A useful way to see it is to rearrange the sentence:

• La decisión no me extraña.

That makes the structure clearer:

• La decisión = subject
• no extraña = verb
• me = indirect object

Spanish often allows a different word order from English, so the subject does not always come first.

Because Spanish has more flexible word order than English.

Both of these are possible:

• No me extraña la decisión.
• La decisión no me extraña.

The version with la decisión after the verb can sound more natural in many contexts, especially when the speaker is commenting on something already known or when the important part is the reaction No me extraña.

So the sentence order is normal and natural, not strange.

Good question. It depends a lot on the variety of Spanish.

In Spain, extrañar commonly means:

• to surprise
• to seem strange

So No me extraña is a very common way to say:

• That doesn’t surprise me
• I’m not surprised

In much of Latin America, extrañar very often means:

• to miss someone or something

For example:

• Te extraño = I miss you

So this is a very important regional difference.

It often feels impersonal in English, because we usually say:

• I’m not surprised

But grammatically in Spanish, it is not truly impersonal here. The verb still has a subject, either expressed or understood.

In your sentence, the subject is stated:

• la decisión

In other cases, the subject might be a whole clause:

• No me extraña que haya dimitido.

So it is better to think of the pattern as:

• Something doesn’t surprise me

rather than as a subjectless structure.

Yes, absolutely, if the context already makes clear what does not surprise you.

For example, in conversation:

• —Ha rechazado la oferta.
• —No me extraña.

That is very common and natural.

When you include la decisión, you are making the thing that does not surprise you explicit.

Yes. That is also correct.

• No me extraña la decisión
• La decisión no me sorprende

Both can express a very similar idea.

However, No me extraña is a very common everyday phrase in Spain and often sounds especially natural in conversation.

A small nuance:

• sorprender is more directly to surprise
• extrañar in Spain can carry the sense of to seem surprising/strange

But in many contexts, they overlap.

Because la decisión is not an indirect object here, and it is not a direct object referring to a person.

The a you may be thinking of is either:

1. the personal a, used before a specific person as a direct object, or
2. the preposition used with some indirect objects

Here, la decisión is the subject, so no a is needed.

The indirect object is already shown by me.

Because Spanish often uses the definite article where English may or may not.

Here la decisión usually refers to a specific decision already known in the context.

So it sounds natural to say:

• No me extraña la decisión.

If you said just decisión, it would generally sound incomplete or unnatural in this kind of sentence unless it appeared in a different structure.

Yes. You can change me to any indirect object pronoun:

• No te extraña la decisión. = The decision doesn’t surprise you
• No le extraña la decisión. = The decision doesn’t surprise him/her/you formal
• No nos extraña la decisión. = The decision doesn’t surprise us
• No les extraña la decisión. = The decision doesn’t surprise them/you plural

The rest of the sentence stays the same unless the subject changes.

Then the verb must also become plural.

For example:

• No me extrañan las decisiones.

Why?

• las decisiones = plural subject
• so the verb becomes extrañan

This is a very useful check: if you are unsure what the subject is, change it to plural and see what the verb would do.