Iranian here. I felt I needed to clarify a few things and just explain a bit more (though I may have biased views or information)

Reasons: Even though the economy was the starting fire and a massive reason to the protests, the entire protest is about changing the government. The chants are like this:
"Death to (the) dictator"
"This is the last battle, Pahlavi will return"
"This year is the bloody year, Seyyed ali will be overthrown"

There are many non-ending underlying reasons for these protests (not ordered):
1. Economy has gone to shit. The Rial has lost 98% of it's value compared to 10 years ago (which was already bad). So you must feel what it's like to save up for a car or a home and wake up to see your money lost half it's value overnight. The Iranian buying power is now destroyed, meaning even surviving is hard.

2. Unemployment is through the roof, especially with the Educated. Many engineers are now doing the Uber equivalent

3. Housing prices are insanely high. To buy an average apartment in Tehran with an average job you would need to work for 30-40 years straight without eating anything (and that's if the dollar stays consistent). Other cities aren't better either

4. Inequality is destroying people's minds. Some people get jobs because they're connected. Some people have free Internet access (while the majority don't). Some people get accepted to universities while the geniuses stay out. Some people have water while others don't. Sexism is on top of all of it.

5. No water no gas no electricity no internet for hours or sometimes days.

6. Iranians always have to find loopholes to do things (use any outside service) because sanctions, that are put on because of stupid government policies.

7. The majority of people do not support geopolitical government policies like supporting hammas, houthies, Hezbollah and fighting with the US and isreal. Many also don't support nuclear programs.

8. No freedom of speech (I'm afraid writing this). No freedom of expression and clothing and basically no freedom of ideology/religion. Islamic ideologies are above all.

9. Constant repression and human rights violation. The people have been protesting since the regime came into power (some notable ones are: 1999,2003,2009,2018-2019,2019-2020,2022,2026). Many Iranians have been or seen a protest and have lost someone or got violently beaten in them.
Apart from protests, the islamic theocracy controlling every person (hijabs, men and women hanging out) every day in schools, universities, streets and... Makes people resent them

10. For the youth specifically, other than all the other problems, there is sarbazi (mandatory military duty) and konkur exam (university entrance exam) which puts a massive toll on their minds and they feel like they're having their youth stolen

All of this makes people want to get rid of them altogether, even if it has hefty costs.

The oppositions:
There are many different groups like democrats, communists and monarchists. But most people don't fall into either one, and support Reza shah because he is the only real opposition that also has a promising future (and most Iranians are right-leaning so it's not a surprise). Also he has often stated that he will hold an election and there won't be an absolute monarchy where the shah has all the power.

The current atmosphere:
From this many unsuccessful protests, and gaurds shooting bullets, people are scared to go outside. But as more people go outside the others are less scared and this makes a feedback loop.
Also the security gaurds are less violent than 2022 and 2018 but they're still very violent and still loyal to the government as many of them are IRGC soldiers, recruits from very poor families or recruits from arab countries (Hezbollah and others). They usually get paid very well for soldiers. So they're still pretty loyal but that could change a lot.

Yeah, that was about it. Ask me any questions while the internet is up