The phrase "d“Deserve to" is my current favorite English phrase.

English here is an adjective, so it needs to have a noun after it: to achieve that, you can just swap the sentence structure around a bit.

A while ago, I watched one ofthe TED talks "Why 30 is not the new 20".

A TED talk is a noun so needs to have an article “the/a” before it.

The structure sounds more natural as above :)

This speech iwas about how significant being twenty-something is(/“in your twenties”) is, ?? even when lifespan is extended. ??

“Twenty-something” is more commonly used casually to describe a certain person who looks in their twenties: e.g. “Then the twenty-something year old shop assistant said hello to me”. I won’t keep correcting it but I would use being “in one’s twenties” when describing the general group of people :)

I don’t really understand the last bit :( it doesn’t really make sense

I would also use past tense “was” here, it sounds more natural even if the speech is still available on YouTube etc.

The most impressive part is "was when he said, “I believe that every single one of twenty-something deserves to know that claiming 20your twenties is one of the simplest, yet most transformative, things you can do for work, for your happiness, maybe even for the world.

Formal written English generally writes out the numbers instead of using the digits, unless you’re talking about statistics/figures. Since you’re talking about age, say “twenty”. ESPECIALLY don’t use both digits and words in the same sentence.

The rest is perfect :)

I think that the phrase "deserves to" makde it a powerful, inspiring and unforgettable speech.

Again, you need the article “a” before the noun “speech”.

“Deserves to” sounds better to me (maybe because it’s a direct quote from the speech you quoted earlier on, and also because “deserve to” is not a form of the verb, the infinitive is “to deserve to”.

It would either be “made it” or “makes it” (not “make it”) but I would use past tense “made it”.

As far as I can remember, I haven't learnt this phrase from someanyone.

“learnt” is the past form of “to learn”

The word "phrase "to deserve to" exactly deserves to be know forn by English learners like me.

“Phrase” (or “verb” would be what I would use because it’s not really a phrase” because it’s more than one word.

Either “deserves to be known by” (passive) or
“English learner like me deserve to know the phrase “to deserve to”.”

The phrase "deserve to" is my currently my favourite phrase in English.

A while ago, I watched one ofthe TED talks "Why 30 is not the new 20".

Thise speech iwas about how significant being twenty-something is even when lifespan is extended.

Using past tense as you are describing a video you have watched in the past.

The most impressive part is "for me is when they said “I believe that every single one of twenty-something deserves to know that claiming your 20s is one of the simplest, yet most transformative, things you can do for work, for your happiness, maybe even for the world.

“For me” to highlight it’s your opinion

I thinkfeel that the phrase "deserve to" makde it a powerful, inspiring and unforgettable speech.

This is a more natural way of saying this sentence

As far asFrom what I can remember, I haven't learnt this phrase from someanyone.

The wordphrase "deserve to" exactly deserves to be know forn by fellow English learners like me.yself