Yes, it's definitely a worrying trend. Bitcoin users who value their privacy will now have to look for alternative ways to protect their identities and transactions. Another option is to use privacy-focused coins like Monero or Zcash, which provide enhanced privacy features. However, it's essential to note that even these coins are not entirely foolproof and can also be subject to regulatory scrutiny.

Mixing services is just a part of many privacy related methods when dealing with bitcoin isn't it?

I mean you still have the option to create your own full bitcoin node^[1] to avoid leaking information about your transactions and balances to third parties, avoiding KYC-compliant P2P services, using wallet with coinjoin^[2] functionalities and practicing coin control^[3].

[1] https://en.bitcoin.it/wiki/Full_node
[2] https://en.bitcoin.it/wiki/Privacy#CoinJoin
[3] https://en.bitcoin.it/wiki/Privacy#Coin_control

When Bestmixer was seized, around the same time Bitblender which was one of the biggest mixers also stopped Business, but this did not stop other mixers from taking over and thriving

Closure of Chipmixer is not the end of Bitcoin Mixing service. More will always pop up. In fact, as we speak, there are a handful of trustworthy alternatives. For example, cryptomixer is no small mixer and has been in operation since 2016.

There is an important difference between Mixers and privacy wallets/coinjoin, in my opinion.

Mixers are a service, which need to be hosted and maintained by operators, which makes them vulnerable in a way or another. However, Privacy wallets and coinjoin are supposed to be open source and in the case of coinjoin, it can become a decentralized standard, in that case an government cannot realistically take down something which does not require a centralized host to work properly.

What I think it is going to happen is that the agencies will get tougher on exchanges and casinos, so they won't be allowed to take coin-joined coins in any way shape or form in the future.

How many mixers were seized in history? Only two (BestMixer and ChipMixer) or more than two in history?

I think so but governments will not stop their hunt for 'illegal' mixers. They will even enforce more law regulations against mixers. I don't think mixers will be eliminated completely but they will be challenged more by governments.

Maybe governments will enforce some requirements on mixers and allow their operations but how is what I don't know. They can not ask license on business which they consider as illegal.

This will not be the end of Bitcoin mixing services. Just like it wasn't the end when Bestmixer.io was shut down in 2019. Mixing will continue to operate. One of them will grow big and will become the target of the authorities. If successful, the authorities will have it seized or shut down. But it will only cause more to grow. Tornado Cash was also shut down, but since it is simply a protocol, an open-source tool, there will come a time when a similar platform will come out.

I believe it would make more sense if the casinos and exchanges mixed both KYC and detection of coinjoined Coins. It is more useful for law enforcement to know who is using those anonymized coins, in a context where tools to enhance coin privacy are highly available through open source protocols and wallets, like wasabi and Trezor (Satoshilabs is planning to release CJ for both Trezor one and Trezor T in the future).

For example, if I deposited anonymous coins in Binance, since they had my personal information, they could inform authorities to add me in some list of people to pay attention to. If they did not have that personal information, they could not do, so only restrict my account to some level.

Privacy of transactions will always be hunted by authorities. They want information about each transaction that a crypto user did but mixers make it difficult for them. No doubt some old mixers got banned due to involvement in illegal activities but more mixers in the market can be used to keep up your privacy while making transactions. Here is the list of all mixers that you may use to mix your BTC with basic details.
These are the list of all the BTC MIXERs by LeGaulois
I hope this list might help you. And I have a question for you if you do not mind answering. I had a conservation with my local community member about the illegal usage of the mixer, he said most of the usage of all mixers is for only illegal activities but I insist that people want to use it for good purposes like to get privacy but some might be using it for there own agendas by harming its(mixer) purpose. So can you tell if is it true like all mixers are intentionally involved in illegal activity? Just have a curious question. Because none of my friends ever used a mixer, not me. So I was curious about its experience and usage of it. People who have used it must have a better answer to the question.

Don't know why you're bringing up the topic now that the issue has gradually being forgotten.
And btw, if you're not dealing with your Bitcoin illegally then there is nothing for you to be scared about, the only time I have used a mixer was when I was testing the mixer that I'm currently promoting I just had to check and see how it works and not because of privacy whatever.
And you shouldn't forget that they are so many users here that haven't used any mixer since they got into Bitcoin are they not still alive?