Immediately looks for justifications when there's an incident of police brutality

It's not immediately clear to me what you are implying with this statement. Is it that you think that any justification of the use of force by the police is un-libertarian, is it that you think it is un-libertarian to question an official verdict of "police brutality", or something else?

Pro-death penalty

This is a difficult statement to tackle. I would argue that, at the very least, it is not as cut and dry as you appear to be making it out to be. There could certainly be arguments both for, and against capital punishment from a libertarian perspective. This being said, a libertarian would generally seek to minimize the power, and authority of the state, and fully recognize its fallibility. Being cognizant of the state's fallibility, I would argue, is mutually exclusive with the death penalty -- if the state wrongfully imprisons someone, there is no turning back, in the case of newly found evidence exonerating the individual, should they be killed.

Has both of these flags, doesn't notice the contradiction between them

I tried to do some research on the "Blue Lives Matter"/"Thin Blue Line" flag(s), and the Blue Lives Matter movement, but, I must say, it is very difficult to find any unified information, vision, or platform for it -- it's hard to find evidence of the idea that the Blue Lives Matter flag is mutually exclusive to the Gadsden Flag (which is a symbol of libertarianism). I am, of course, not naive to the fact that a very specific faction of people enjoys sporting that symbol, but I must be careful in laying any judgement, as I am frequently annoyed when I come across misappropriations of the Gadsden Flag, which, in my opinion, is one of the best symbols of libertarianism that exists. I would, at the very least, say that I don't believe that libertarianism is opposed to law public enforcement.

Aside: If you have any good resources that outline the actual symbolism represented by the flag, then I would really appreciate it if you could share it so that I might try to ameliorate my understanding.

~~Protesting banned books, voter roll purges, anti-protest laws, Assange, Snowden, etc.~~ Complaining about cancel culture

Protesting banned books

If books are banned by law, this a violation of freedom of speech, so supporting that would indeed be non-libertarian.

voter roll purges

Would you mind specifying what you mean by this? I'm not familiar with it.

anti-protest laws

Again, this is a violation of freedom of speech, as well as freedom of assembly, freedom of association, etc. so supporting it would, indeed, be non-libertarian.

Assange, Snowden

What specifically about them are you referring to? Are you talking about their leaking of state-classified information, their individual principles, or something else?

In favor of anti-trans bathroom laws

Any law which would prevent a private establishment from setting its own such rules would, indeed, be non-libertarian.

Believes drugs and prostitution should remain illegal

Any laws that restrict the freedoms of the individual, if those freedoms do not infringe on those of others, is, indeed, non-libertarian.

"I am a libertarian, I just think the left has gone too far recently and needs to be pushed back against!"

I don't understand what you are implying here. There are plenty of non-libertarian things that the "modern left" political faction supports.

Only actual libertarian principles are being pro-2A and hating the IRS

While, yes, supporting the 2A falls in line with libertarian principles, I'm not convinced that abolishing the IRS would be. The IRS's purpose is to collect taxes. A libertarian doesn't necessarily have to be completely opposed to taxation, and if there exists taxes, then you need state agency to collect them -- of course, a libertarian would certainly seek to minimize taxation to the greatest extent feasible.